Fairey Delta 2
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 Fairey Delta 2 was the first jet aircraft to exceed in level flight. On 10 March 1956, it set a new world speed record of, exceeding the previous official record by. The Delta 2 held the absolute World Air Speed Record for over a year. It continued to be used for flight testing, and was allocated to the Royal Aircraft Establishment in 1958.
A testbed aircraft was required to verify design calculations and wind tunnel results for the Concorde "ogee delta" wing design so one of the aircraft was extensively rebuilt as the BAC 221. On 1 May 1964, the modified aircraft performed its first flight. The FD2 was also used as the basis for Fairey's submissions to the Ministry for advanced all-weather interceptor designs, culminating in the proposed Fairey Delta 3 to meet the F.155 specification; however, the FD3 never got past the drawing-board stage.
Development
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. 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 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. 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.
Following on from the Delta 1, the Ministry of Supply requested that Fairey conduct a further model programme for the purpose of transonic investigations. However, Fairey did not find this proposal attractive, believing that a piloted aircraft would be mandatory if the project was to produce any worthwhile data. Fairey commenced work on a highly swept twin-engine aircraft; however, the Ministry lacked enthusiasm for the twin-engine configuration, largely due to an existing rival project underway to produce a twin-engine supersonic aircraft – this would become the English Electric Lightning. 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 would directly originate. Accordingly, the Ministry issued Air Ministry Specification ER.103 for the project, ordering that a pair of prototype aircraft be produced.
File:Fairey FD2 XG774 Farnborough 08.09.56 edited-2.jpg|thumb|right|The first Delta 2 WG774 in its original design format landing at Farnborough Airport in 1956 during that year's SBAC Show using its 'droop snoot', 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. 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. Data that had been obtained from the earlier model work also proved to have been highly valuable to the Fairy Delta 2 programme. 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 September 1952, technical drawings of the Fairey Delta 2 were issued and the development proper commenced. From the project's beginning, Fairey designed the parameters of the FD2 to intentionally exceed that which was necessary only to achieving Mach 1. 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. In total, a pair of flight-capable aircraft were produced: Serial numbers WG774 and WG777. WG777, the second to be manufactured, was very similar to WG774 except the underwing flap system was not incorporated. There were also a few differences in terms of equipment and instrumentation. In addition to the two flying aircraft, a single static test airframe was also completed.
Flight testing
On 6 October 1954, WG774, the first FD2 to be completed, conducted its maiden flight, flown by Fairey test pilot Peter Twiss. According to aviation author Derek Wood, the Delta 2 "proved to be an exceptional aeroplane from the outset". On 17 November 1954, WG774 suffered an engine flameout on its 14th flight when internal pressure build-up collapsed the fuselage collector tank, closing off the fuel supply to the engine, while heading away from the airfield at 30,000 ft, 30 mi after taking off from RAF Boscombe Down. Twiss managed to glide to a dead-stick landing at high speed on the airfield. Only the nose gear had deployed, and the aircraft sustained damage that put it out of action for eight months. 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. Despite this refusal, Fairey was able to base the Delta 2 temporarily in France and later in Norway so that the tests could be performed. The French government required the tests to be insured against damage claims; this demand had proved unacceptable with two British insurance companies quoting a premium of about £1,000 per flight; however, a French company insured them for £40. No claims were ever received in either France or Norway.
On 15 February 1956, WG777, the second Delta 2, performed its maiden flight from RAF Boscombe Down; piloted by Twiss, the aircraft reached transonic speeds during this first flight. Following the final contractor check flight on 14 April 1956, WG777 was formally accepted, upon which it was assigned to the RAE's high-speed research programme, conducting measurement, stability and handling research. In September 1956, both aircraft performed flight displays at the Farnborough Airshow in Hampshire. The Delta 2 was typically used to conduct a multitude of tests including aerodynamics characteristics, handling, and stability performance.
Testing of the Delta 2 was carried out in France for some time, in part due to Fairey's good relations with Dassault Aviation of France and the French Air Force. 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 observed these trials, learning a great deal about delta wing aircraft from the FD2. Dassault had flown the MD.550 Mystère-Delta design in June 1955, which Wood notes "bore a striking resemblance to the layout of the FD.2". The MD.550 design would proceed to be manufactured as the successful Dassault Mirage III fighter, which first flew two days after the return of the FD.2 from the tests in France. 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. The substantial rebuilding of the aircraft to participate in further research was first mooted in that same year as well. In its original configuration, the Delta 2 performed flight tests, interspersed with periods of storage, up until mid-1966.