On 6 October 1954, the Delta 2 made its maiden flight, flown by Fairey test pilot Peter Twiss; two aircraft would be produced.

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.

[5] 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.

[7][8] Events such as the Korean War and rapid advances in the fields of supersonic aerodynamics, structures and aero engines by the British aircraft industry had the effect of increasing demand and the potential capabilities of new fighters.

In addition to developing improved versions of existing and emerging fighters such as the Hawker Hunter and Gloster Javelin, there was an appetite for even more promising entirely new aircraft.

[8] As a remedy to this, in October 1951, Sir Robert Lickley of Hawker Aircraft was promptly recruited as Fairey's new Chief Engineer and became a major force behind the programme.

[11] 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.

In addition to seeking very high performance, the design adopted a general configuration and structure that would be readily adapted to future military requirements, so that it could potentially become a fighter aircraft.

[17] In October and November 1956, a total of 47 low-level supersonic test flights were conducted from Cazaux Air Base, Bordeaux, France; a detachment of Dassault engineers closely observed these trials, learning a great deal about delta wing aircraft from the FD2.

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.

[16] According to Wood, many members of the development team recognised that the FD2 possessed huge speed potential, beyond any other British-built aircraft in existence of that time.

[22] However, Fairey found the Ministry of Supply unsupportive, having adopted the prevailing belief being that manned military aircraft would soon be replaced by guided missiles.

[23] 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 endeavor.

For this purpose, a variety of ground measurement cameras were set up at Chichester and at RNAS Ford, various ground markers were installed at specified locations, and radar tracking from RNAS Ford and RAF Sopley; flights by Gloster Meteors and de Havilland Venoms for calibration purposes were also conducted by the RAF.

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.

[26] According to Wood, consequences included in-depth studies of the FD2 airframe by the United States and the major reshaping of military aircraft programs in France.

Fairey itself was elated with the achievement, viewing it as a practical endorsement of their design, and fuelled the firm's ambitions to establish a family of supersonic fighters on its basis.

Combat equipment would have been provisioned, including a Ferranti-built aircraft interception radar 1495 and de Havilland Firestreak air-to-air missiles.

[29] 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 60,000 feet (18,000 m) 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.

[17] 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.

[17] A final attempt was made to progress a Delta 2 derivative into production came during the late 1950s for the new German Air Force of West Germany.

[34] 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 design aimed to improve both supersonic wave drag with high leading-edge sweep and low thickness/chord ratio at the root,[36] and low-speed lift through flow separation at the leading edge which creates a rolled up vortex on top of the wing.

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.

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.

Considerable cost-cutting measures and management strategies, such as PERT, were adopted by BAC in order to not overrun on the fixed-price contract it had been issued for the work; some engineers were allegedly frustrated by this as apparent means of further improvement were dismissed.

[41] At high throttle settings, considerable suction into the inlets was generated; in the event of a sudden down-throttle motion by the pilot would result in air "spilling" out of the intakes, which was a concern because it could flow above the wing and disrupt the vortex.

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.

[8] The Delta 2 has a cylindrical cross-section fuselage, which closely fitted the Avon engine, and smoothly flowed into a long tapered nose.

[8] The internal space housed both the main undercarriage and a total of four fuel tanks without any bulges or fairings in the wing, while four spars provided for significant structural strength.