Appendix I

ASW AND AEW

The bulk of this book covers the evolution of frontline naval combat aircraft such as fighters and attack aircraft as they made the transition from piston engine to jet power, and with the changes that were necessary to the ships in order that they could operate the new types coming into service. However, other aircraft were needed to carry out less glamorous but nevertheless essential roles, notably anti-submarine warfare (ASW) and Airborne Early Warning (AEW). In general these were all propeller-driven aircraft and normally did not require the shipboard modifications needed by the jets, although they did benefit from such advances as the angled deck and mirror landing sight. Brief details of these aircraft are given below.

ASW — THE ROYAL NAVY

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 The ancient Swordfish was obsolete and withdrawn from service while the most suitable aircraft, the Grumman Avenger, had to be returned to the US under Lend-Lease agreements.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 (see Chapter 2) 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, which are described in Chapter 2. 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.

ASW — THE US NAVY

For the US Navy the development of ASW aircraft was not accorded such a high priority as they had numerous Grumman Avengers, which were initially quite suitable for the task and could operate from the smaller Escort Carriers that the US Navy retained for ASW use. However, the increasing amount of electronic equipment that needed to be carried, as well as the increasing use of large weapons such as homing torpedoes meant that a larger aircraft was desirable. In fact, the US Navy avoided an increase in size by splitting up the ASW task into two separate functions, the search or hunting role and the attack or killer role.

The aircraft to carry out this role actually evolved from a Grumman project started in 1944 to design a replacement for the TBF/TBM Avenger. A similar mid wing layout was adopted and the crew of two sat side by side under a single glazed canopy. Power was provided by a single 2,300 hp R-2800-46 Double Wasp radial piston engine but this was supplemented by a single Westinghouse 19XB turbojet in the tail. Prototypes were ordered in February 1945 under the designation XTB3F-1 and the first of these flew on 19 December 1945. However, flight tests revealed that boost provided by the small jet engine was not as much as had been hoped and it was removed, although this did leave additional load-carrying capacity and the design was recast in the ASW role as the Grumman AF-2 Guardian. This had a more powerful 2,400 hp R-2800-48W radial engine and was actually produced in two complementary versions. The AF-2S was a pure weapons carrier, although a short range APS-30 radar was carried in a pod under the starboard wing, while the AF-2W carried two additional crew members in the rear fuselage and mounted an AN/APS-20 long-range search radar in an under fuselage radome. The Guardian was built in some numbers, with 193 AF-2S and 153 AF-2Ws delivered, along with another forty AF-3S, which was equipped with a Magnetic Anomaly Detector (MAD) in a retractable boom extending aft of the tail assembly. Guardians remained in service until 1957 when the last reserve units relinquished their aircraft.

The Guardian’s replacement came from the same Grumman stable and resulted from an attempt to combine the hunter/ killer roles into a single airframe. Naturally, this led to a much larger aircraft and the result was the high-winged twin-engined Grumman S2F-1 Tracker. Following a development contract being awarded in 1950, the first Tracker flew on 4 December 1952 and production examples were delivered to a test and evaluation squadron (VX-1) at NAS Key West in July 1953. The first operational squadron (VS-26) was formed in February 1954 and the Tracker was subsequently deployed aboard all types of operational carriers, including some escort carriers (CVEs) utilised in the ASW role. Although a relatively large aircraft, the Tracker could be accommodated aboard the smaller carriers due to its short overall length and compact dimensions with wings folded. A total of 1,120 Trackers were built by Grumman and a further 100 were built by de Havilland Canada for the Canadian Navy as the CS2F-1. The Tracker was also operated by several other navies, including those of Australia, Brazil, Argentina and the Netherlands, which all deployed them aboard carriers, while Italy, Japan, Korea and Thailand were among those who operated Trackers from shore bases. The Tracker remained in frontline US Navy service until the mid 1970s, by which time it was being replaced by the jet-powered Lockheed S-3 Viking.

AEW — ROYAL AND US NAVIES

It was the US Navy that instigated the concept of a naval airborne early warning aircraft as a result of the damage caused by Japanese kamikaze attacks in the closing stages of World War II. It was vital to detect these low-flying raids as far out as possible and the destroyer picket ships used for this purpose became prime targets themselves. The development of a radar system that could be carried aboard an aircraft for this purpose was code-named Project Cadillac and began in February 1944. The resulting AN/APS-20 radar was fitted to a modified TBM Avenger in August 1944 and delivery of radar-equipped Avenger TBM-3Ws began in May 1945, although operational aircraft were just too late to see service in World War II. Nevertheless a large number of TBM-3s were modified and by the height of the Korean War in early 1953 over 150 were in service. Apart from the radome, the other changes were the removal of all armament including the dorsal turret, a modified rear cockpit to house the radar operator, and two large finlets on the tailplane to counteract the adverse effect of the radome. The accommodation was extremely cramped and the single radar operator could easily be overloaded in a busy action scenario.

In the early 1950s the TBM-3Ws were gradually replaced by AEW versions of the AD Skyraider (described in Chapter 2). Forty-five AD-4Ws were also supplied to the Royal Navy from 1951 onwards, remaining in service until 1960. The size of the Skyraider allowed two radar operators to be accommodated in the rear fuselage, which much improved the service these aircraft were able to offer. Eventually, the Skyraider AEW version was replaced in US Navy service by the Grumman WF Tracer, which was a development of the S2F Tracker in which an enormous radome was fitted atop the fuselage, necessitating the adoption of a wide-span tailplane with twin fins. However, this did not fly until March 1958 and only became operational in 1960, although it subsequently formed the basis for the turboprop Hawkeye, which is still in production today.

The Royal Navy’s replacement for the Skyraider AEW.1 was the homegrown Fairey Gannet AEW.3. This was a development of the basic Gannet design in which a large radome was carried under the fuselage centre section, replacing the weapons bay that was no longer required. The pilot’s cockpit remained in the original position but the rear cockpits were deleted and two radar operators were accommodated in a cabin within the fuselage. However, the Gannet AEW.3 did not fly until August 1958. It then became operational in July 1960 when aircraft of C flight, 849 Squadron, embarked on the recently commissioned carrier HMS Hermes.

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