Vulcan and Victor - their mini delta precursors

Tony Buttler examines the scale test-beds that preceded the Victor and the Vulcan – and V-bombers that might have been

The short-lived first Avro 707, VX784.

Such was the advanced nature of the new wing shapes selected for the ‘second generation’ of V-bombers – the Avro Vulcan and the Handley Page Victor – that it was thought prudent to prove the radical designs before the full-scale hardware was built.

The Valiant, from Vickers, was seen as the ‘safe’ bet in the original three-cornered V-bomber programme. Its moderately swept wing did not really push the boundaries, unlike the delta-winged Avro 698 and the crescent-winged HP.80 proposals which generated much concern in the Air Ministry. Means to address these anxieties were soon to be followed up.


Mini deltas

A well-established method to test out new concepts was to fly piloted scaled-down aircraft to assess their aerodynamics. In 1948, two onethird scale Type 707s (VX784 and VX790) were ordered from Avro under Specification E15/48. They were to investigate any problems that might be experienced with the Vulcan’s delta wing at low speeds and altitudes.

Two half-scale Type 710s (VX799 and VX808) were also required to cover the high-speed part of the envelope. But such was the level of additional development work needed to produce this separate design that they were soon cancelled.

The two 707s were to use as much existing equipment as possible: for example, a Gloster Meteor cockpit canopy. Avro test pilot Sqn Ldr Eric ‘Red’ Esler made VX784’s first flight on September 4, 1949, but he lost his life on the 30th of the month when the little delta crashed near Blackbushe in Hampshire.

Avro 707A WD280 displaying its modified wing leading edges, a feature introduced on production Vulcans.

More 707s were ordered. Meanwhile VX790’s nose was extended to improve the aerodynamics, its fin enlarged and undercarriage changed, and it had an ejection seat fitted (unlike VX784). In this new form, VX790 was retitled as a Type 707B, Wg Cdr ‘Roly’ Falk making its first flight on September 6, 1950.

In February 1951, VX790’s upper rear fuselage was revised with a ‘hump’ to improve the airflow into its 3,500lb/st (15.6kN) Rolls-Royce Derwent 5 turbojet. By late 1952 testing from the Royal Aircraft Establishment at Farnborough, Hampshire, had shown that a tailless aeroplane could have excellent flying qualities. A landing accident, however, ended VX790’s flying career in September 1956.


Wing buzz

Specification E10/49 of 1949 covered two examples of a new ‘high speed’ 707A to be capable of 576mph (927km/h) at 36,000ft (10,973m). Given the serials WD280 and WZ736, they introduced a new wing with root intakes more representative of the Vulcan, although the forward fuselage was unchanged.

Falk took WD280 on its first flight on June 14, 1951, by which time the 707s were making little direct contribution to the full-size bomber, much of the design of which had been frozen. Falk took the prototype Avro 698, the first Vulcan, VX770 into the air for the first time on August 30, 1952.

However, the discovery of wing ‘buzz’ – a high-frequency vibration – in the 707A at high speed and while pulling ‘g’ at extreme altitude proved important. To deal with the problem, compound sweepback and a kink to the outer portion of the leading edge were introduced. The inner part of WD280’s outer wing had its sweep angle reduced while the outermost wing was swept even more, a change that would be incorporated on production Vulcans.

In 1956, WD280 went to Australia to undertake low-speed research and continued flying well into the 1960s. It still exists, preserved in Melbourne. First flown on February 20, 1953, WZ736 was used at Farnborough on several projects, such as automatic landing trials at Martlesham Heath, Suffolk, before being struck off charge in 1962. It’s displayed at the Museum of Science and Industry, Manchester, on loan from the RAF Museum.

Layout of the unbuilt Avro 710.
Avro 707B VX790 after its intake had been modified with a ‘hump’ to improve the engine airflow.

Might have been: AW.56

The Armstrong Whitworth AW.56 was a flying wing with no tailplane, the company declaring that problems presented by sweptback wings were easier to solve using a tail-less aircraft. Lateral and longitudinal control was to be achieved using two surfaces in tandem on each outer wing, called the ‘corrector’ and ‘controller’ respectively.

It featured four Rolls-Royce AJ.65 turbojets housed in the wing roots, with a fifth in the rear fuselage fed by its own intake on the upper fuselage. Span was 120ft (36.6m), all up weight 113,000lb (51,257kg) and projected cruising speed 581mph (936km/h) at 36,000ft (10,973m).

Model of the AW.56.
Avro 707C WZ744 had side-by-side seating.
Superb image of the four 707s (VX790, WD280, WZ736 and WZ744) taxiing out in front of the control tower at Farnborough for the 1953 SBAC airshow.


The last Avro mini-delta built was a side-by-side two-seat version, without ejection seats, the Type 707C. Sqn Ldr T B Wales took it on its maiden flight on July 1, 1953 before it went to the Aeroplane and Armament Experimental Establishment at Boscombe Down, Wiltshire, to provide pilot experience on deltas. From 1956 it was used on some of the earliest trials with electrical control systems and today it’s held by the RAF Museum at Cosford, Shropshire.

Overall, the 707s’ benefits to the Vulcan programme were not substantial, but they proved to be very useful research aircraft in their own right. They’re also remembered for their spectacular paint schemes – VX784 was silver, VX790 blue, WD280 originally salmon pink and then bright red, WZ736 orange, and later yellow, and WZ744 silver.

The first high-speed 707A, WD280, had wing root intakes, a cleaner arrangement than the earlier dorsal format.
The HP.88, VX330, used a fuselage similar to another high-speed aircraft, the Supermarine Type 510.

Tragic crescent

Meanwhile Handley Page was asked to build a two-fifths scale single-seat research aeroplane to test the aerodynamics of the Victor’s crescent wing. Designated HP.88, two were ordered to Specification E6/48 – VX330 and VX337 – but only the first was completed.

Demands on Handley Page to gear up for the full-size V-bomber were such that the HP.88 was subcontracted to Blackburn at Brough in the East Riding of Yorkshire. A fuselage similar to the Supermarine Type 510 research aircraft’s was adopted and attached to a 0.4 linear scale HP.80 wing and an all-moving tailplane. It did not fully represent the bomber as it had a high wing – the HP.88’s wing was mounted lower on the fuselage.

Using the East Yorkshire airfield of Carnaby, near Bridlington, VX330 first flew on June 21, 1951, piloted by Gartrell ‘Sailor’ Parker, Blackburn’s chief test pilot. Testing progressed well before the aircraft moved to Stansted in August to prepare for the Farnborough airshow.

On August 26, VX330 broke up over the Essex airfield and was destroyed, killing its pilot, Flt Lt Douglas Broomfield. It’s understood that oscillations at low altitude resulted in the fuselage failing. Inertial coupling between the all-moving tail and the powered controls had put a massive load on the airframe.

Rear view of the ‘taildragger’ HP.88.
Model of the Avro 698 as first proposed to B35/46.

This tragic loss did not delay to the Victor development programme: Hedley ‘Hazel’ Hazelden was at the controls of the prototype Victor, WB771, on Christmas Eve, 1952.


Might have been: SB.1

One of the Shorts submissions for the V-bomber contest was the SB.1, a flying wing, tail-less project utilising the ‘aeroisoclinic’ wing proposed by Professor Geoffrey Hill. It featured novel all-moving wing tips and the concept was tested by the SB.1 glider, which was rebuilt as the SA.4 Sherpa scale aircraft flown in the 1950s. It is now part of the Ulster Aviation Society’s collection at Long Kesh in Northern Ireland.

A second ‘first generation’ V-Bomber design, the Sperrin, was also produced and flew in prototype form, but was ultimately discarded.

The SB.1 had five Rolls-Royce AJ.65s – one housed in the fuselage and two in each wing mounted in pairs one above the other. Span was 114ft (34.75m), all up weight 115,000lb (52,164kg) and projected cruising speed 576mph (927km/h) at 47,000ft (14,326m).

Project drawing of the Short SB.1.
The Handley Page Victor Phase 4 proposal.


The Vulcan and Victor were the winners of a major design competition made against Specification B35/46. Two companies lost out and were not invited to build prototypes. Armstrong Whitworth proposed its AW.56 and Shorts the SB.1, both of which employed advanced wing configurations. (See the panels.)

Handley Page artwork depicting the HP.80 as it was proposed to the design competition.

As with most major design programmes, the Avro 698 and the HP.80 went through considerable evolutions prior to the designs being declared frozen and metal cut. What became the Vulcan altered in layout considerably as the design matured and the drawing offices at both Avro and Handley Page envisaged wingtip fins at an early stage.

There were many proposed developments of the Victor and Vulcan, including two supersonic derivatives, but neither came close to being built. The Avro 732 of 1956 was to have been powered by eight de Havilland Gyron Juniors, four in pairs side-by-side in the fuselage and the others in pairs in underwing nacelles. Other than its delta wing concept, it owed little to the Vulcan.

The so-called ‘Phase 4’ Victor resulted from studies of the behaviour of production examples at high speeds. These introduced a refined fuselage with area ruling and reheat to provide supersonic capability while retaining the existing B.2 wings and tail.

The development and trials programmes that created the Victor and the Vulcan were extensive, yet both of these radical designs proved to be relatively straightforward to bring into service. They were great successes, becoming long-term backbones of the UK’s nuclear deterrent.

The Avro 732 concept of 1956. The under-fuselage weapon is unidentified.