Fairey Delta 2

The Fairey Delta 2 or FD2 (internal designation Type V within Fairey) was a British supersonic research aircraft produced by the Fairey Aviation Company in response to a specification from the Ministry of Supply for investigation into flight and control at transonic and supersonic speeds.

The aircraft was the first to exceed 1000 mph, and held the World Air Speed Record for over a year.

Design and development

The first Delta 2 WG774 in its original design format landing at Farnborough in 1956 during that year's SBAC Show using its 'droop snoot'

The design was a mid-wing tailless delta monoplane, with a circular cross-section fuselage and engine air-inlets blended into the wing roots. The engine was a Rolls-Royce Avon RA.14R with an afterburner. The Delta 2 had a very long tapering nose which obscured forward vision during landing, take-off and movement on the ground. To compensate, the nose section and cockpit drooped 10°, in a similar way to that used later on Concorde. Two aircraft were built: Serial numbers WG774 and WG777.

The FD2 was used as the basis for Fairey's submissions to the Ministry for advanced all weather interceptor designs leading to the Fairey Delta 3 for the F.155 specification, but it never got past the drawing board stage.

Testing

The first FD2 was aircraft WG774 which made its maiden flight on 6 October 1954, flown by Fairey test pilot Peter Twiss. On 17 November 1954, WG774 suffered engine failure on its 14th flight when internal pressure build-up collapsed the fuselage collector tank when heading away from the airfield at 30,000 ft (9,100 m), 30 mi (50 km) after take-off from Boscombe Down. The ex-Fleet Air Arm pilot 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 sidelined it 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.^[1]

The FD2 test programme did not resume until August 1955.^[2] On 10 March 1956 the aircraft broke the World Air Speed Record, raising it to 1,132 mph (1,811 km/h), an increase of some 300 mph (480 km/h) over the record set in August 1955 by an North American F-100 Super Sabre. It thus became the first aircraft to exceed 1,000 mph (1,600 km/h) in level flight. This record stood until 12 December 1957 when it was surpassed by a McDonnell JF-101A Voodoo of the United States Air Force.^[3]

BAC 221

BAC 221 at the Fleet Air Arm Museum. The forward extension and general curving layout can be seen.

Development of the Concorde was based on a new type of delta wing developed at the Royal Aircraft Establishment (RAE) known as the ogee-ogive design. This design aimed to improve both supersonic performance through limited span, and low-speed performance through the creation of vortexes between the wing and fuselage that increased air velocity over the wing and thereby increased lift. In order to make full use of this effect, the wing should be as long as possible, and highly swept at the root. Continued studies of this basic concept led to the ogee layout.

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 Fairy began discussions about converting one of the Delta's to the support the ogee wing. Fairy 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 center 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.^[4]

Further work was disrupted in 1960 when Fairey was purchased by Westland Aircraft, who handed further development of the conversion to Hunting Aircraft. In July the program moved to Bristol, now part of the larger British Aircraft Corporation. Bristol suggested two ways forward, a minimal conversion with a sub-optimal wing but no other major changes, or a maximal conversion with a larger six foot extension to the fuselage and a much taller landing gear more typical of the type expected on the Concorde. Both would also be equipped with a new Elliott Brothers stabilization system, and have the engine intakes moved under the wing. A contract for the "maximal" conversion was sent in September, and WG774 was flown to Bristol's Filton plants on the 5th. After a delay, construction began in April 1961 and the newly christened BAC 221 was completed on 7 July.^[4]

Several problems were encountered during the conversion. The new lengthened landing gear required more hydraulic fluid, which required a larger reservoir to hold it, pump to move it quickly enough through the system, and so on through the hydraulic system. Retaining the relatively simple intakes but only on the bottom of the wing presented the issue that the airflow into the engine was from below, as opposed to the entire compressor face, so the ducts were extended above the wing to split the airflow evenly. This produced a noticeable bulge on the upper surface of the wing. No attempt was made to fit variable intakes. At high throttle settings there is considerable suction into the inlets, and sudden down-throttle results in air "spilling" out of the intakes, which was a concern because it could flow above the wing and disrupt the vortex. Small lips were added to the intakes to help prevent this, but this proved to cause intake buzzing. Changes to the ducts, helped by Rolls-Royce, addressed this.^[4]

One major advantage of the new design was larger fuel capacity, which was a major problem for the original FD.2. The FD had often run out of 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, but Mach 1.6 was reached in testing.^[4]

In total, it 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 in this form on 1 May 1964.^[5] It was used from 1964 until 1973.

Survivors

• WG774, in BAC 221 form, is now on display alongside the British Concorde prototype at the Fleet Air Arm Museum at Yeovilton.
• WG777, is preserved at the Royal Air Force Museum at RAF Cosford, alongside many other supersonic research aircraft.

Operators

 United Kingdom

• Royal Aircraft Establishment

Specifications (Fairey Delta 2)

WG774 with the original polished-metal finish. It later received yellow "go faster" stripes, followed by a purple and yellow scheme, before conversion to the BAC 221.

Data from ^[6]

General characteristics

• Crew: 1
• Length: 51 ft 7½ in (15.74 m)
• Wingspan: 26 ft 10 in (8.18 m)
• Height: 11 ft 0 in (3.35 m)
• Wing area: 360 ft² (33.44 m²)
• Empty weight: 11,000 lb (4990 kg)
• Gross weight: 13,884 lb (6298 kg)
• Powerplant: 1 × Rolls-Royce Avon 200, 10,000 lbf (44.59 kN)

Performance

• Maximum speed: >1300 mph (>2092 km/h)
• Range: 830 miles (1336 km)

See also

• Flight airspeed record
• Peter Twiss
• Aerospatiale-BAC Concorde

Related development

• Fairey Delta 1

Aircraft of comparable role, configuration and era

• Dassault Mirage
• English Electric P1A
• Bristol 188
• Avro 707C

Related lists

• List of experimental aircraft

References

Wikimedia Commons has media related to Fairey Delta 2.

Notes

Bibliography