It was developed to test the tailless thick delta wing configuration chosen for the Avro 698 jet bomber, later named the Vulcan. In particular, the low-speed characteristics of such aircraft were not well known at the time. Aerodynamically, it was a one-third scale version of the Vulcan. The second prototype, VX790, was built to the 707B configuration, featuring a longer nose, alternative cockpit canopy, a modified wing with (51°) sweep, and an elongated nose wheel leg for a greater angle of incidence during both landing and take offs. The twin-seat 707C, the final variant, which had been designed to perform delta wing orientation training with the Royal Air Force; however, no production aircraft would ultimately be produced. The handful of 707s that were produced were largely used for flight testing purposes.
On 4 September 1949, the first Avro 707 performed its maiden flight; low-speed testing began shortly thereafter. Higher speed testing commenced in late 1953 using the third aircraft, the first 707A. After development of the Vulcan had been completed, the four surviving 707s continued to be flown as general research aircraft. The prototype 707C was involved in various research programmes, the majority of which were unconnected to the Vulcan. Numerous tests involving the type were conducted by both the Royal Aircraft Establishment (R.A.E) and the Aeronautical Research Laboratories in Australia. During the early 1950s, the Avro 707 performed several public appearances at the Farnborough Airshows. The last flying Avro 707 was grounded during 1967; three aircraft have been preserved and placed on static display in museums.
Design and development
An Avro 707A in flight, 1951.
The Avro 707 originated as a "proof-of-concept" delta wing aircraft that was principally the work of Stuart D. Davies, Avro's chief designer. It was a relatively compact aircraft that initially incorporated a wing with about 50° sweep, without a horizontal tail on a fin with trailing edge sweep. The trailing edge of this wing carried two pairs of control surfaces: inboard elevators and outboard ailerons. These flight surfaces worked in conjunction with a conventional rudder.[2] Retractable airbrakes were also provided above and below the wings.[3] The aircraft featured all-metal stressed-skin construction.[2]
The prototypes were ordered by the Ministry of Supply to fulfil Specification E.15/48, which called for a low-speed research aircraft that would be a one-third scale version of Avro's B.35/46 design for a strategic bomber. Production of this aircraft was accelerated by using several components from other aircraft, such as the canopy of the first prototype being taken from a Gloster Meteor.[N 1][5][6] The Avro 707 programme provided valuable insights into the Vulcan's flight characteristics, most of the information coming from the second and third prototypes which flew before the Vulcan. A half-scale aircraft, the Avro 710, was cancelled when it became clear that it would be less time-consuming to develop a high-speed variant of the Avro 707 instead.[7][8]
All Avro 707s were powered by a single Rolls-Royce Derwent centrifugal turbojet engine. The air intake on the first prototype and later 707B was located on the upper rear fuselage.[9] Some aircraft were outfitted with ejection seats.[10] In total, five Avro 707s were completed.[11][N 2]
On 4 September 1949, the first Avro 707, VX784, performed its maiden flight from RAF Boscombe Down, Squadron Leader Samuel Eric Esler, DFC, AE, was at the controls.[2] Two days later, it was statically displayed at the Farnborough Airshow. However, testing with the first prototype was cut shortly when, on 30 September 1949, it crashed near Blackbushe during a test flight, killing Esler.[12][2] The loss of the first prototype led to the construction of the second prototype being temporarily halted while the design was re-examined, leading to several refinements being implemented.[13]
The next prototype, VX790, renamed the 707B, had a longer nose, different cockpit canopy, a wing of different (51°) sweep and a longer nose wheel leg 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 first prototype, although this was later modified to a NACA design. It first flew on 6 September 1950; the aircraft quickly proved to be relatively docile in flight.[2][13] Both the 707 and 707B were largely flown to test low speed characteristics.[2]
The third aircraft, designated 707A, WD280 was built for higher speed testing.[14] Experience with the dorsal intake of the earlier 707 and 707B had shown that as speed increased, the cockpit induced turbulence which interrupted the intake airflow, thus the intakes were repositioned to the wing roots.[15] It was not designed for supersonic flight as it was felt this would necessitate both power-operated flight controls and far greater engine power.[14] When the Vulcan appeared, it looked very much like an enlarged 707A. Later, this 707A was used to test the compound leading edge sweep subsequently used on all Vulcans. Although the first Vulcan prototype was already flying, a second 707A WZ736 was produced to speed the development programme. It made its maiden fight on 20 February 1953.[14]
The final variant was the two-seat 707C; originally four examples were ordered by the RAF with the intention of conducting orientation training for flying aircraft with delta wing configurations using the type.[14] The 707C was provisioned with a wider cockpit to accommodate a "side-by-side" seating arrangement and dual flight controls. However, the production order was cancelled; accordingly, only the sole prototype, WZ744, was built.[15] The 707C had its maiden flight on 1 July 1953 and was ultimately employed in other research that did not involve Vulcan development.[16][8]
Two Avro 707As, a 707B and a 707C with both Vulcan prototypes at the SBAC Farnborough Air Show in September 1953
Even after the Vulcan development phase was over, the four surviving 707s, in individual bright blue, red, orange and silver (natural metal) colour schemes, continued in use as research aircraft.[16][8] After the compound sweep investigation,[14] and a period with the Royal Aircraft Establishment (R.A.E) carrying out handling trials with powered controls,[17] the first 707A went to the Aeronautical Research Laboratories in Australia for low-speed delta wing airflow measurements. The second 707A was also at the R.A.E from June 1953 for aerodynamic and later, automatic control investigations.
During September 1952, the Avro 707B joined the R.A.E.,[17] becoming one of the aircraft used by the Empire Test Pilots School from January to September 1956,[18] when it was damaged on landing, and broken up at R.A.E. Bedford.[15][13] The two-seat 707C joined the R.A.E. in January 1956; perhaps its most substantial research contribution was to the development of fly-by-wire control systems, one of the first of their kind, and fitted with a side stick controller. This aircraft was flying with the R.A.E. until September 1966 when it achieved its full airframe time.[19]
The Avro 707s made numerous public appearances at the Farnborough Airshow throughout the 1950s. During 1952, the first prototype Vulcan flew with the 707s A and B and in 1953, the four surviving Avro 707s flew alongside the first two Avro 698 Vulcan prototypes.
The Avro Blue Steel was a British air-launched, rocket-propelled nuclear armed standoff missile, built to arm the V bomber force. It allowed the bomber to launch the missile against its target while still outside the range of surface-to-air missiles (SAMs). The missile proceeded to the target at speeds up to Mach 3, and would trigger within 100 m of the pre-defined target point.
The Avro Vulcan is a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe and Company (Avro) designed the Vulcan in response to Specification B.35/46. Of the three V bombers produced, the Vulcan was considered the most technically advanced, hence the riskiest option. Several reduced-scale aircraft, designated Avro 707s, were produced to test and refine the delta-wing design principles.
A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ).
The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final V bomber to be operated by the Royal Air Force (RAF), the other two being the Vickers Valiant and the Avro Vulcan. Entering service in 1958, the Victor was initially developed as part of the United Kingdom's airborne nuclear deterrent, but it was retired from the nuclear mission in 1968, following the discovery of fatigue cracks which had been exacerbated by the RAF's adoption of a low-altitude flight profile to avoid interception, and due to the pending introduction of the Royal Navy's submarine-launched Polaris missiles in 1969.
The Gloster Javelin is a twin-engined all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. It was a T-tailed delta-wing aircraft designed for night and all-weather operations and was the last aircraft design to bear the Gloster name. Introduced in 1956 after a lengthy development period, the aircraft received several upgrades during production to its engines, radar and weapons, including support for the De Havilland Firestreak air-to-air missile.
The Bristol Type 188 is a supersonic research aircraft designed and produced by the British aircraft manufacturer Bristol Aeroplane Company. It was nicknamed the Flaming Pencil in reference to its length and relatively slender cross-section as well as its intended purpose.
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The Fairey Delta 2 or FD2 is a British supersonic research aircraft that was produced by the Fairey Aviation Company in response to a specification from the Ministry of Supply for a specialised aircraft for conducting investigations into flight and control at transonic and supersonic speeds. Features included a delta wing and a drooped nose. On 6 October 1954, the Delta 2 made its maiden flight, flown by Fairey test pilot Peter Twiss; two aircraft would be produced. The Delta 2 was the final aircraft to be produced by Fairey as an independent manufacturer.
The Saab 210 is an approximately 70% scale research prototype for the double-delta configuration of the Saab 35 Draken supersonic fighter. It became known by the unofficial nickname Lilldraken. Its first flight was on 21 January 1952.
The Hawker Hotspur was a fighter aircraft developed between the wars for the Royal Air Force. It was designed in response to Air Ministry Specification F.9/35, which required a powered turret as the main armament to replace the Hawker Demon. It was developed from the Hawker Henley, a competitor for the light bomber role but put into production as a target tug, and fitted with a Boulton-Paul powered four gun turret.
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The Boulton Paul P.111 is an experimental aircraft designed and produced by the British aircraft manufacturer Boulton Paul. It was amongst the first aircraft designed to explore the characteristics of the tailless delta wing configuration.
The Avro 730 was a planned Mach 3 reconnaissance aircraft and strategic bomber that was being developed by Avro Aircraft for the Royal Air Force (RAF). It had been originally envisioned as a very high-speed aircraft to perform aerial reconnaissance missions, conforming with the requirements of Air Ministry Specification OR.330. Avro subsequently decided to modify the design of the proposed 730 in order to accommodate its arming with nuclear weapons; this change therefore meant that the type would be able to perform the nuclear weapons delivery mission as well, which had been called for under Air Ministry Specification RB.156T which sought a high speed reconnaissance-bomber aircraft.
The Short SB.5 was a "highly unorthodox, adjustable wing" British research aircraft designed by Short Brothers in response to the UK Air Ministry requirement ER.100; to provide input for the design of the English Electric P.1 by testing the low speed flight characteristics of various configurations of wing-sweep required for supersonic flight. The tailplane could be mounted either on top of the fin ("T-tail") or below the fuselage. The tests ultimately confirmed that the original P.1/Lightning design was an effective configuration for high speed flight.
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The Nord Gerfaut (Gyrfalcon) was a French delta-wing experimental research aircraft. It was the first European aircraft to exceed Mach 1 in level flight without the use of an afterburner. A pair of aircraft were built for the primary purpose of investigating the transonic regime. The Gerfaut I conducted its maiden flight in 1954; it was followed by the improved Gerfaut II two years later. Both aircraft were flown for several years for experimental purposes, being significantly upgraded over time. During the course of these test flights, the second prototype establishment multiple time-to-altitude world records. In the late 1950s, the type was used to flight-test various aerial missiles. Both aircraft performed their final flights in 1959; they were subsequently used as targets at the Military Test Range at Cazaux.
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The Sud-Ouest SO.6020 Espadon (Swordfish) was a French post-war prototype interceptor designed and built by SNCASO during the late 1940s. The French Air Force judged the design a failure despite some records being set and cancelled plans to put it into service in 1951. Only four aircraft were built and they were later modified to serve as testbeds for the mixed rocket and turbojet-powered SNCASO SO.9000 Trident program. Only one badly damaged aircraft survives.
References
Notes
↑ "Off-the-shelf" parts included an Avro Athena main undercarriage leg and Gloster Meteor nose leg.[4][2]
↑ The last three Avro 707s flew after the Vulcan's first flight on 30 August 1952.
Citations
↑ Force V: The history of Britain's airborne deterrent, by Andrew Brookes. Jane's Publishing Co Ltd; First Edition 1 Jan. 1982, ISBN0710602383, p.43, 44, 47, 48.
Blackman, Tony (2007). Vulcan Test Pilot: My Experiences in the Cockpit of a Cold War Icon. London, UK: Grub Street. ISBN978-1-904943-88-4.
Buttler, Tony (April 2007). "Avro Type 698 Vulcan (Database)". Aeroplane. Vol.35, no.4.
Buttler, Tony; Delezenne, Jean-Louis (2012). X-Planes of Europe: Secret Research Aircraft from the Golden Age 1946-1974. Manchester, UK: Hikoki Publications. ISBN978-1-902-10921-3.
Cooper, Peter J. (2006). Farnborough: 100 years of British Aviation. Hinkley, UK: Midland Books. ISBN1-85780-239-X.
Harlin, E.A.; Jenks, G.A. (1973). Avro: An Aircraft Album. Shepperton, Middlesex, UK: Ian Allan. ISBN978-0-7110-0342-2.
Hewitt, John C. (2003). Ireland's Aviator Heroes of World War II. Mercier Press Ltd. ISBN1-78117-388-5.
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