Deltas

After the war, and with the benefit of access to German research, there was interest in the delta wing as the solution to problems of transonic flight. A number of contracts was issued for research aircraft.

Boulton Paul P.111 and P.120

Specification E.27/46 was issued for investigation of delta wings at transonic speeds. Boulton Paul produced the P.111, VT935, powered by a single Nene RN2 which first flew on 6 October 1950. It was very compact and had an exceptionally thin 45° delta wing and triangular fin and rudder, with wing and fin-tips removable for comparative trials; thus the wing-span could be adjusted between 25ft 8ins and 33ft 6ins. The aircraft was flown on company-based trials which identified high sensitivity and unduly high landing speed. Late in 1951 a landing accident led to extensive rebuild. The design was changed on the second aircraft, VT951. Designated the P.120, it now featured horizontal tail surfaces atop a revised fin and rudder. It flew from Boscombe Down on 6 August 1952 but crashed on the 29th of the month after 20 flights as a result of loss of the port elevon through wing flutter. The P.111 was rebuilt as the P.111a with alterations to the undercarriage doors and air brakes to reduce landing speed. A long pitot head was fitted in the intake and the anti-spin parachute modified to act as a braking aid. In its new guise the P.111a flew on 2 July 1953 and soon transferred to the RAE where it served until 1958. It is preserved at Coventry.

Fairy F.D.1

Fairey, with its close association with naval flying, had considered the possibility of a vertically launched delta-wing fighter for use from ships. Specification E.10/47 sought a delta-winged research aircraft to investigate the possibilities of the configuration and Fairey responded with the F.D.1. Initially 40 10ft span models were constructed and flown from Aberporth, then a tank-landing craft in Cardogan Bay and latterly Woomera. Power for these models was from a single Beta 1 engine of 1,800lbs thrust with two 600lb thrust rockets for inital boost. The first successful launch was on 1 may 1949. The F.D.1 proper was extremely small with a span of 19ft 6 ins and it featured a broad delta wing and small delta tailplane on top of the fin. Powered by a single Derwent engine without the intended booster rockets the only of three ordered to be built, VX350, flew on 12 March 1951. By now interest in a VTO fighter was diminished but the aircraft was used for trials until 1956 when its undercarriage was torn off in an emergency landing.

Avro 707

In support of the decision to build the Avro 698 (later Vulcan) against specification B.35/46 it was decided to accelerate development through the use of 1/3 scale models. Two low-speed aircraft (707B) were ordered under specification E.15/48 and one high-speed aircraft (707A) to E.10/49. A second order called for a further 707A and a two seat trainer to become the 707C. The first 707 was VX784 with a split dorsal air intake for its Derwent engine and fin with extended strake. It first flew 4 September 1949 but crashed on 30 September killing pilot Eric Esler. The next aircraft was 707B VX790 which was similar to the prototype but with a 12ft longer fuselage and revised dorsal intake. It flew on 6 September 1950 and eventually joined the RAE fleet at bedford where it was struck off charge in 1957. Avro 707A WD280 had wing root intakes similar to those fitted to the Type 698 and a longer dorsal fin. In due course it was fitted with a cranked wing which was transferred to the Vulcan and later sent to Australia where it flew from 1956 to 1967 presently being preserved in Melbourne. The second aircraft was WZ736 which flew from Waddington on 20 February 1953; neither this aircraft nor the sole trainer were much involved in Vulcan development but they flew on trials duties until 1967 with the RAE. It is preserved at Manchester. The 707C had side-by-side seating and the wing root intakes of the 707A. The only example was WZ744 which flew on 1 July 1953; it is now preserved at Cosford.

Armstrong Whitworth AW58

Armstrong Whitworth received a contract against specification E.16/49 for a design study for a Mach 1.2 aircraft in 1958 and their response was an advanced 59° swept wing design. Serials WD466 and 472 were allocated but in due course the project was cancelled. The Company was invited to propose a revised delta design but that was also cancelled before construction had begun.

Fairey FD.2 and BAC 221

An advanced design was commissioned from Fairey to meet specification ER.103 for a delta winged aircraft for transonic and supersonic research. Two aircraft were ordered with the serials WG774 and WG 777. The wing had a straight leading edge with 60° sweep and power was a single reheated Avon R.A.16. An unusual feature, lent in due course to Concorde, was a drooping nose to enable the pilot to see ahead on the ground. WG774 was completed in 1954 and the first flight was from Boscombe Down on 6 October 1954. By late 1955 Mach 1.1 had been achieved and on 10 March 1956 Peter Twiss established a new world air speed record at 1,132 mph. The second aircraft flew on 15 February 1956 and after serving with the RAE at Bedford it was retired in 1967, now being preserved at Cosford.
In 1959 specification ER.193D was issued for a high speed research aircraft to test the intended ogival wing of the Concorde. BAC took WG774 from Bedford and converted it to the intended configuration with revised wing and extended fuselage. It flew on 1 May 1964 at Filton and was retired in 1974 having provided invaluable data on the high speed performance of the wing. It is preserved at Yeovilton.

Handley Page H.P.115

The Supersonic Transport Advisory Comittee was formed in 1956 and among its early tasks was the identification of potential design problems with a slender delta wing and the means of examining them. Specification ER.197D resulted in the H.P.115 the sole example of which, XP841, flew on 17 August 1961 at RAE Bedford. It had a narrow delta wing of 74.7° sweep and 20ft span while overall length was 50ft. The single Viper engine was mounted in a nacelle above the rear fuselage and the aircraft had a fixed undercarriage. The aircraft provided a considerable amount of invaluable data for the Concorde programme over the next four years and it was finally retired in 1974, currently being preserved at Yeovilton.