Background During the late 1940s,
Fairey Aviation, a British aircraft manufacturer, had become interested in
delta wing technology and proceeded to submit multiple submissions based on the delta wing concept to the
Ministry of Supply. The Ministry, being interested in these proposals, issued orders for models to test the envisioned delta wing, the first of which being built in 1947; testing was performed by the
Royal Aircraft Establishment (RAE). The program was succeeded multiple times, including an investigation into potential
VTOL operations, leading to further flight tests of the delta wing models to be conducted in
Cardigan Bay,
Wales and
Woomera, Australia. In 1947,
Air Ministry Specification E.10/47 was issued for a full-scale piloted delta wing aircraft, resulting in the
Fairey Delta 1, which conducted its maiden flight at
RAF Boscombe Down on 12 March 1951. Meanwhile, throughout the early and mid 1950s, the
Royal Air Force (RAF) had developed an intense desire to advance the performance of their aircraft; in particular, the service sought new fighter aircraft that would be capable of routinely flying at very high speeds and high altitudes as a long-term replacement for its existing inventory of roughly 700
first-generation jet fighters. At the time, there was a perception that Britain was trailing behind in supersonic aircraft design, and there was pressure to correct this. Following on from the Delta 1, the Ministry of Supply requested that Fairey conduct a further model programme for the purpose of
transonic investigations. In February 1949, it was suggested that Fairey examine the prospects for a single-engine transonic aircraft as an alternative; by the end of the year, the company had produced their new project, out of which the Fairey Delta 2 (FD2) would directly originate. Accordingly, the Ministry issued Air Ministry Specification ER.103 for the project, ordering that a pair of prototype aircraft be produced. described by its inventor as a sectional fuselage At the time, Fairey was mostly known for producing naval aircraft, such as the
Fairey Swordfish biplane and the
Fairey Firefly monoplane; the design team lacked experience with high speed projects. Early development work on the FD2 would be hindered by two major factors, a lack of available information on wing and intake design, and the declaring of
Fairey Gannet as a 'super-priority' by the British government, which had necessitated delays.
Flight testing On 6 October 1954,
WG774, the first FD2 to be completed, conducted its
maiden flight, flown by Fairey test pilot
Peter Twiss. Twiss, who was shaken up by the experience but otherwise uninjured, received the
Queen's Commendation for Valuable Service in the Air. One result of the crash was a temporary halt on the test programme, which did not resume until August 1955. During early flight tests, repeated supersonic test runs over southern Britain were conducted; as a result of these flights, a number of claims for damages against the
supersonic booms were received. Tests of the Delta 2's low-level supersonic flight capability were disrupted due to the perceived heightened risk posed by supersonic booms being produced during lower altitude flight; as such, the Ministry of Supply refused to allow this testing to be performed over the UK. Wood credits the Delta 2 as having served to confirm Dassault's theories and supporting the Mirage III program. Once the manufacturer's testing was completed, both aircraft were formally handed over to the RAE. In addition to providing the institution with useful information on the characteristics of the 60°-swept delta wing, from 1958 onwards, the FD2 aircraft participated in various research projects and flying trials, including an investigation into the performance of ejector-type propulsive
nozzles. During early flight testing, Twiss came to realise that the Delta 2 would be capable of speeds above and proposed that it be flown on with the aim of breaking the current air speed record, which had then been held since 1955 by a
North American F-100 Super Sabre. However, Fairey found the Ministry of Supply unsupportive, having adopted the prevailing belief being that crewed military aircraft would soon be replaced by
guided missiles. Fairey had great difficulty in obtaining permission for the attempt. Twiss stated that the situation was "curiously inverted" from expectations, having expected that government agencies would have been enthusiastically pressing for a record-breaking flight as a means to bolster national prestige. According to Wood, Fairey was confronted by a combination of scepticism and apathy from
Her Majesty's Civil Service, to the extent that it appeared that the government were opposing the endeavour. The Ministry of Supply sought to avoid any association with a speed record bid while
Rolls-Royce, the FD2's engine manufacturer, also dismissed the attempt, claiming that the air intakes were unsuitable for speeds around Mach 1.5, and that the Avon engine would disintegrate at such speeds, despite an absence of any practical data to support this assertion. In spite of this opposition, Fairey sought to continue, and were given permission to proceed. Regardless, Fairey chose to continue with the record attempt. The achievement had also made the Fairey Delta 2 the first jet aircraft to exceed 1,000 mph (1,600 km/h) in level flight. News of the new airspeed record quickly spread and had a prompt impact upon the international aeronautics industry, typical reactions being shock and near-disbelief.
Proposed derivatives Fairey produced a number of proposals which would have involved the further development of the Delta 2. The first of these was another experimental aircraft, designated as the
ER.103/B, which would have paired the wings of the FD2 with a revised fuselage, which had a greater span and length. Fairey claimed that the ER.103/C would be capable of attaining Mach 2.26 at an altitude of . In particular, Fairey pursued
Operational Requirement F.155, which called for a two-seat fighter equipped with radar and missiles with suitable performance to achieve an altitude of and Mach 2 within six minutes of taking off; while the company thought that their design would be fully capable of meeting the specified requirements, it was believed that the complete weapon system would not be fully developed until 1962. Thus, Fairey proposed that a simpler interim aircraft, if selected, could be available by 1960 or potentially earlier. In addition to the Gyron engine of earlier proposals, the proposed fighter was to be equipped with a pair of
de Havilland Spectre rocket engines that were mounted in fairings on the rear fuselage. The
high-test peroxide (HTP) fuel for the rocket engines was stored in tanks held in underwing
fairings and within the wing's
leading edge, separate from the turbojet engine's fuel storage. It featured a two-man crew, a pilot and radar operator/navigation, seated in a side-by-side configuration. However, on 4 April 1957,
Duncan Sandys, the
Minister of Defence, announced the effective termination of nearly all fighter aircraft development for the RAF, instantly removing the F.155 requirement. Running against a competing American bid with the
Lockheed F-104G Starfighter, Fairey joined forces with Rolls-Royce and Dassault in a collaborative effort to produce a delta wing aircraft capable of reaching Mach 2 to meet the German demand for fighter aircraft. The proposal would have seen Dassault produce the wings, Fairey manufacture the fuselage, and Rolls-Royce provide the engine, which was intended to be a
Rolls-Royce Spey engine with reheat; Belgium also played a role in the programme. However, the American lobby proved to be too strong, in part due to the subsequently uncovered
Lockheed bribery scandals that had influenced German decision makers, and the F-104G was selected instead. This was the end for the FD2 as a fighter concept; the concept never saw any use as a production aircraft; Wood summarised the state of affairs as "the harvest was left to France to gather".
BAC 221 The
Concorde design used a then-new type of delta wing that was being developed at the RAE known as the
ogee or ogival delta design. This design aimed to improve both supersonic wave drag with high leading-edge sweep and low thickness/chord ratio at the root, and low-speed lift through flow separation at the leading edge which creates a rolled up vortex on top of the wing. The added suction under the vortex increases lift by an amount known as vortex lift. The wing root chord should be as long as possible, and highly swept where it meets the forward fuselage. Continued studies of this basic concept led to the ogee layout and it eventually became apparent that a series of full-scale flight tests would be necessary for its validation. . The forward wing extension and curved leading edge can be seen Low-speed testing of the concept was already being provided by the
Handley Page HP.115. Although high-speed performance appeared to be predictable, a dedicated testbed aircraft was desired, especially for drag measurements. As early as 1958, the RAE and Fairey began discussions about converting one of the Delta 2 prototypes to support the ogee wing. Fairey proposed stretching the fuselage a further three feet to better match the long planform, with the wing extending out onto the drooping nose. However, calculations showed that this extension was not great enough to counter the forward moving
centre of pressure (CoP) that resulted from the extended planform, and there were also concerns that the over-wing engine intakes would swallow the vortex above the wing. In early September 1960, it was agreed that the "maximal" conversion would proceed; on 5 September of that year,
WG774 was flown to Bristol's Filton facility. Various problems were encountered during the conversion. The newly lengthened landing gear required more
hydraulic fluid, which required a larger reservoir to hold it, a higher capacity pump to move it quickly enough through the system, and so on through the hydraulic system. One major advantage of the new design was its larger fuel capacity, which has been a major problem for the original FD2. The Delta 2 had often run low on fuel while still accelerating, thereby never reaching its full performance. The modifications for the 221 meant it was not capable of the same levels of performance; however, speeds of Mach 1.6 were attained during its test flights. In total, the BAC 221 featured a new wing, engine inlet configuration, a Rolls-Royce Avon RA.28, modified vertical stabilizer and a lengthened undercarriage to mimic Concorde's attitude on the ground. It first flew on 1 May 1964. The sole 221 was used for varied flight testing from 1964 until 1973, after which it was placed on public display. ==Design==