A Short Seamew AS.1 anti-submarine aircraft lands aboard the Royal Navy aircraft carrier HMS Bulwark (R08) during trials, 15 July 1955.
At the end of World War II, the Royal Navy faced a shortage of modern ASW aircraft. The ancient Swordfish was obsolete and withdrawn from service while the most suitable aircraft, the Grumman Avenger, had to be returned to the US under Lend-Lease agreements. Consequently, a series of stopgap measures were put in hand until a new ASW aircraft could be developed. These included bringing back into service a dozen Fairey Barracuda Mk.IIIs, modified to act as anti-submarine patrol aircraft, in late 1947 to equip 815 Squadron, which retained them until 1953. Their replacement was actually the Grumman Avenger of which 180 were supplied to the Royal Navy from 1953 onwards under the MDAP scheme to boost NATO strength. These were basically similar to the TBM-3E as used by the US Navy but were designated Avenger AS.4 and AS.5 in Royal Navy service.
Up to the introduction of the Avengers, the most numerous carrier-based ASW aircraft was the Fairey Firefly in its AS.5 and AS.6 versions. However, in an effort to provide a more mission-orientated aircraft a new version was developed as the Firefly AS.7. The most noticeable change was in the engine installation, which now featured a chin-mounted annular radiator instead of the underwing radiators on the earlier versions. To cope with the increased workload, a third crew member was carried and the two observers/radar operators sat in the rear cockpit, which was covered with a large, bulged clear-view canopy. The addition of this and the chin radiator required a substantial increase in fin area to maintain directional stability. A modified wing planform of increased span was incorporated and, although capable of being fitted with underwing hardpoints to carry offensive ordnance, the AS.7 was intended to be used only in the search role with surface ships or other aircraft being directed onto any submarines located. The prototype AS.7 flew on 22 May 1951 and was followed by 150 production aircraft, although only two frontline squadrons were equipped with the type. In service the handling characteristics of the Firefly AS.7 were markedly inferior to the earlier Mks.4/5/6 and consequently most of those built were produced as trainers (Firefly T.Mk.7) and used by second line squadrons for observer training. The poor performance of this aircraft was one reason why the Avengers had to be brought in from America, plugging the gap until a completely new ASW aircraft became available.
This was to be another Fairey product, the turboprop-powered Gannet AS.1. Originally known as the Fairey Type Q, it was produced to Specification GR.17/45 issued in 1945, calling for a two-seat anti-submarine and strike aircraft. The design was based around an Armstrong Siddeley Double Mamba turboprop, which, as the name implied, was actually two 1,000-shp Mamba engines coupled to drive a contra-rotating propeller assembly through a common gearbox. As well as producing the necessary power output, this arrangement had the advantage that one half of the power unit could be shut down in flight to save fuel and extend range and endurance. The first of two prototypes flew in September 1949 but a third prototype flown on 10 May 1951 featured provision for a third crew member in a separate cockpit in the rear half of the fuselage. Although a large aircraft, the Gannet was of a clean design. However, it had a rather portly appearance due to the fact that the weapon load was carried in an internal bomb bay and the crew sat high up above the engine in the nose. The contra-rotating propellers and tricycle undercarriage, coupled with the forward cockpit being set high to give an excellent view, meant that the Gannet was a first-class carrier aircraft and few problems were encountered in the initial deck landing trials by one of the two-seat prototypes aboard HMS Illustrious in June 1950 – in fact, this was the first ever carrier landing by a turboprop-powered aircraft. A complex double-jointed wing-folding system ensured that the aircraft would fit in the hangars of current British carriers. An ASV search radar antenna was housed in a retractable dome under the rear fuselage and this meant that the Gannet was able to carry out the complete ASW mission, including both the search and attack roles.
In March 1951 the Gannet was one of the aircraft to be allocated Super Priority status and was ordered in substantial numbers. After some delays while a number of handling problems were sorted out, the first Gannets reached the Royal Navy in April 1954 and three operational squadrons were formed by mid 1955, including 826 Squadron aboard HMS Eagle and 824 Squadron aboard HMS Ark Royal. Subsequently, the Gannet served with a dozen frontline squadrons and was exported to Australia, West Germany and Indonesia. An improved Gannet AS.4 flew in April 1956 offering a more powerful version of the Double Mamba as well as other detail improvements. The Gannet served as a frontline ASW aircraft until withdrawn between 1958 and 1960 as helicopters gradually took over the ASW role.
Although the Gannet met the requirements of Specification GR.17/45, it had a number of competitors. One of these was the turboprop version of the Short Sturgeon, which used two single Mambas and carried the radar in a prominent fixed chin mounting under the nose. Designated Short SB.3, the prototype flew in August 1950 but whereas the original Sturgeon had been a delightful aircraft to fly, the SB.3 proved something of a handful, particularly in asymmetric flight with one engine failed – a problem that was neatly avoided by the Gannet’s Double Mamba installation. Consequently, little development work was undertaken and the two prototypes were scrapped in 1951.
The Gannet’s other competitor came from the Blackburn stable in the form of the B-54 (or YA.5 under the then current SBAC designation system). Superficially this resembled the Gannet, being similar in size and adopting the same layout except that the pilot and observer were set further back, seated over rather than ahead off the wing. Like the Gannet, an enclosed weapons bay was set into the lower fuselage and a retractable radar dome was positioned behind it. Power was to be provided by a Napier Double Naiad turboprop, similar in concept and power output to the Double Mamba. However, development of this engine was cancelled leaving the Blackburn team in limbo. It was decided to complete three prototypes powered by Rolls-Royce Griffon piston engines and these were designated YA.7, the first flying in September 1949. When the Admiralty requirement was altered to include a third crew member, the second prototype was modified to incorporate this and also had a revised wing planform and taller fin and rudder assembly. In this form the aircraft became the YA.8 and flew in May 1950, carrying out carrier trials during the following June. Finally, the third prototype was fitted with a Double Mamba turboprop and this represented the definitive version under the designation YB.1 (company designation B-88). First flown in July 1950, it was unsuccessful in comparative trials with the Fairey Gannet and no production orders were forthcoming.
The Gannet might well have had a stablemate in the shape of the Short Seamew. This aircraft was produced in response to a 1951 Naval Staff requirement for a simple and rugged ASW aircraft, in effect a modern version of the old Swordfish, which could be deployed on smaller carriers or from short landing strips ashore. The Seamew first flew on 23 August 1953 and was ordered into production, both for the Royal Navy and RAF Coastal Command. Powered by a single Mamba turboprop, the Seamew was a simple and rugged design with a tailwheel undercarriage necessitated by the decision to place the fixed radome under the fuselage just forward of the wing. A crew of two was carried, with the pilot and observer sitting well forward under a double canopy. Its performance was not startling but the main requirements of a four-hour patrol duration and carriage of depth charges and sonobuoys in an enclosed weapons bay were met. The test programme revealed a number of handling deficiencies that were being rectified when the whole programme was cancelled in 1957 under the Defence White Paper that year. By that time the Royal Navy had already received seven production aircraft and these were subsequently scrapped.