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De Havilland DH 110 Sea Vixen
The D.H.110 was designed during 1946 to meet the requirements of the Royal Navy for an advanced carrier-based all-weather fighter (Specification N.40/46) and of the RAF for a night fighter (F.44/46). In 1949, orders were placed for seven night fighters and two long range fighter prototypes for the RAF and two night fighter and two strike fighter prototypes for the RN, but the Naval version was later cancelled and the RAF order reduced to two (to Specification F.4/48) on economy grounds.
The mid-set wings have 40 degrees sweepback and conventional ailerons, rudders and Fowler flaps are fitted. The rear portion of the all-moving tailplane is deflected upward separately to avoid trim changes when the flaps are lowered. ‘Dog-tooth’ wing leading edges, air intakes in the wing roots and a large air-brake under the centre-fuselage are fitted.
The tricycle undercarriage has a single wheel on each unit. The main wheels retract inward into the wings, and the nose wheel retracts rearward.
A fire-control radar is fitted in the nose.
The prototypes first flew on 26 September 1951 and 25 July 1952, powered by 7,500 lb st (3405 kgp) Avon RA7s. The pilot occupied a single cockpit offset to port, with the observer alongside in the fuselage nacelle; provision was made for radar in the nose and four 30 mm Aden cannon in the fuselage. After the loss of the first prototype and selection of the Gloster Javelin to meet the F.4/48 requirement, the second D.H.110 was modified to have an all-flying “slab” tailplane, variable gearing in the aileron and tailplane primary control circuits, reduced ventral fin area and cambered leading edge extensions outboard of the wing fences.
Royal Navy interest in the D.H.110 revived in 1952 and while the second prototype was used for preliminary deck landing trials, a new semi-navalised prototype was built as the Mk 20X, making its first flight on 20 June 1955. An intensive period of flying trials was undertaken in the first half of 1959 by the Sea Vixen FAW.1 in the hands of No.700 “Y” Flight at RNAS Yeovilton.
The first production Sea Vixen flying on 20 March 1957. It was followed by the fully-navalised Sea Vixen FAW Mk 1 which had folding wings, revised tail unit, longer stroke undercarriage, new GEC radar, nosewheel steering, ejection seats, 11,230 lb st (5 100 kgp) Avon 208s, and armament of 28 x 2-in (5,08-cm) rockets in retractable packs in the nose plus four Firestreak JR AAMs or rocket pods or two 1,000-lb (454-kg) bombs under wings. 114 Sea Vixen FAW Mk 1s were built and the first Royal Navy squadron (No 892) was formed on 2 July 1959. This version subsequently equipped five other squadrons, including No 766 all-weather training and No 899 HQ Squadrons
The Sea Vixen FAW Mk 2 differed in having extra fuel in forward extensions of the tail booms and provision to carry Red Top AAMs in place of Firestreaks. Prototypes flew on 1 June and 17 August 1962, and were followed in 1963-66 by 29 new production Mk 2s and 67 converted Mk 1s. Service use continued until 1972, after which about two dozen Sea Vixens were converted to pilotless drones for use as targets at the Aberforth range.
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