The Avro Shackleton was designed as a long-range maritime patrol aircraft and was heavily derived from the Avro Lancaster bomber. However, despite being based on a Second World War-era airframe, it was developed to meet the needs of British maritime forces during the early days of the Cold War when tensions between the Soviet Union and the West were growing.

Avro designed the aircraft with durability and longevity in mind. As such, the Shackleton saw a long and impressive service with the Royal Air Force up until 1991, despite taking a lot of its design features from a Second World War aircraft.

The Shackleton was praised for its long flight times and saw overseas service in South Africa.

Contents

• Origins
• Development
• Service and Variants
• Legacy
• Specifications

Origins

The Shackleton’s development began following a specification issued by the British Air Ministry in 1946. The specification called for a long-range maritime patrol aircraft that could fly substantial distances and be used by the Royal Air Force Coastal Command.

Following the end of the Second World War, the British government became concerned about the expansion of the Soviet navy and its relatively close proximity to the British coast.

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Particular concern was felt about the Soviet Union’s growing fleet of submarines which had been caught patrolling within or close to UK territorial waters. Along with other NATO forces, Britain looked to expand and adjust their armed forces to meet these concerns.

Avro had already considered upgrading their existing Lancaster bomber into a new anti-submarine and patrol aircraft, although this was more for operations against Japan in the far east during the war.

After the war had finished, Lancaster’s chief designer Roy Chadwick began working on an updated version of the bomber that could be used as a maritime patrol aircraft. He presented it to the British Air Ministry and the Coastal Command as the Avro Type 696. Both the Ministry and RAF Coastal Command expressed their approval.

Work on the new Type 696 aircraft continued, although Chadwick was tragically killed in an air accident in 1947, leaving the Avro team to continue the project without him.

The Type 696 continued to evolve under the Avro team and the look of the aircraft began to gradually shift away from the Lincoln design. It also incorporated elements of the Avro Tudor civilian airliner into the concept and emphasis was also shifted to focusing on endurance.

Development

With the Type 696 taking shape, the design team consolidated their ideas and produced a finished prototype.

Although it was initially referred to as the Lincoln ASR.3 as the project moved towards the prototype phase, Avro named the new aircraft the Shackleton in honour of the explorer Sir Ernest Shackleton and felt the name would live up to the aircraft’s intended ruggedness and range.

For the early prototype models, the centre section of the fuselage was kept from the Lancaster bomber while the wings and undercarriage were lifted from the Tudor.

However, substantial redesigns resulted in a larger fuselage that could accommodate the crew’s equipment and quarters. New undercarriage and wings were also fitted. The Shackleton’s tail still resembled the two-fin variant found on the Lincoln and Lancaster.

Power would be provided by four Rolls Royce Griffon liquid-cooled engines. Each engine would drive a set of contra (opposite rotating) propellers, making the Shackleton the first British four-engine aircraft to have this feature.

The Griffon produced the same power and speed as the Rolls Royce Merlin but Avro opted for the Griffon due to its economical fuel consumption.

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Initially, the armament for the anti-submarine variant consisted of two 20 mm cannons fitted in the nose and a bomb bay that could carry up to nine bombs, three remote-homing torpedoes or depth charges. A canon turret was also placed on the top of the fuselage.

Avro predicted the new aircraft would have an estimated range of 3,000 nautical miles and be able to carry a weight of up to 2,700 kg worth of weapons and onboard equipment for the crew.

The Shackleton completed its maiden flight on the 9^th of March at Avro’s airfield in Woodford, Cheshire. It was done under the control of Avro’s chief test pilot Jimmy Orrell. The test results were deemed as good and Avro continued to add to the prototype’s design.

The aircraft was given air-to-air refuelling capabilities, although this was not ultimately fitted to all of the production models, and the ability to carry sonobuoys (droppable sonar equipment) to enable the Shackleton to participate in electronic warfare at sea.

Once the proving and testing process was completed, Avro put the Shackleton into production and deliveries of the finished airframes was delivered to the RAF in 1951.

Service and Variants

The Shackleton officially began service in 1952 with the RAF’s No. 20 Squadron based at RAF Lossiemouth, Scotland The Squadron was focused on anti-submarine warfare and used the first version of the Shackleton known as the MR1.

However, the Shackleton’s first deployment in a combat situation occurred when it was used as a troop transporting aircraft in 1955 during the Suez Crisis and performed this role extensively at British military bases in Cyprus.

Typically, an RAF Shackleton crew in active service would consist of two pilots, two navigators, a flight engineer, an air electronics officer and four air electronics operators.

Problems with rust and metal fatigue were detected by RAF engineers in the first model and Avro sought to address this in updated variants.

During its service, the Shackleton’s design also had to continually evolve in tandem to keep up with changing submarine technology. The arms race between East and West spurred constant design upgrades and new weapons to outmatch the other, and Avro realised the first variant could become obsolete. Avro produced the Shackleton MR2 and MR3 models, the latter being introduced in September 1955 with an improved fuselage to mitigate rust issues.

The MR3 was developed in response to crew feedback on the earlier variants. The changes consisted of a new tricycle landing gear, updated wings and fuel tanks mounted on the wing tips.

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The cockpit and crew quarters were also fitted with better sound insulation, as earlier versions of the Shackleton had been nicknamed the “Growler” by crews due to the loud and unusual sound the engines produced in the cabin.

The cannon turret on top of the aircraft was removed but rockets were fitted to the wings as a new defensive measurement.

The engines on the MR3 were also modified to feature the new Rolls-Royce Viper 203 turbojets in the engine nacelles for additional takeoff assistance and to give the Shackleton a greater range and speed.

The MR3 Shackleton was also exported abroad and saw service in the South African Air Force (SAAF) from 1953 onwards. The South African government had become concerned about the presence of Soviet submarines spotted off the coast of the Cape of Good Hope. The Shackleton was used to replace the SAAF’s fleet of Short Sunderland aircraft in search and rescue and submarine monitoring roles.

The SAAF Shackleton’s were also used in protecting the South African coast from hazards other than Soviet submarines. In 1971, a fleet of Squadrons were used as part of the clear-up operation following the SS Wafra oil spill off the coast of South Africa by dropping depth charges on the wrecked vessel to sink it and prevent further oil spillage.

International sanctions placed on South Africa due to the government’s apartheid policies somewhat hampered the ability to maintain the fleet and ultimately led to their retirement when spare parts became harder to source. The last Avro Shackleton left South African service in 1984.

However, the Shackleton continued to see success in service with the RAF and was praised by airmen for its durability and range. This was effectively demonstrated during a display at the 1960 Farnborough air show when a Shackleton took off as part of a display and returned 24 hours later.

Avro also updated the design in 1966 for the Shackleton to carry depth charges armed with a nuclear payload to compensate for the fact submarines were able to cruise at deeper depths.

By the late 1960s, the Shackleton’s future in RAF service was called into question when the jet-powered Hawker Siddeley Nimrod was introduced in 1969. The Nimrod carried much of the same equipment featured on the Shackleton but was a more advanced jet design.

Despite this, the entrance of the Nimrod into RAF service did not immediately spell the end of the Shackleton. Initial problems with the Nimrod’s early warning capabilities combined with the unavailability of the Boeing E-3 Sentry prompted the RAF to modify some of their Shackleton’s for Airborne Early Warning (AEW) roles. The modified AEW Shackleton’s were placed into service in September 1971.

Avro had also designed the Shackleton with longevity in mind, as they had done with their other aircraft, and the Shackleton continued to serve with the RAF in an AEW capacity until 1991 when the last Shackleton units were withdrawn from service.

Legacy

After their withdrawal from British and South African service, a number of Shackleton units have survived and been preserved.

Perhaps the most fascinating example is that of Pelican 16: a former SAAF Shackleton that was being flown to RAF Duxford in England in 1944 for preservation as a museum piece. The Shackleton crashed in the Sahara two hours after takeoff. The crew survived and the aircraft sustained light damage, but it remains stranded but preserved in the desert.

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Another Shackleton is displayed at the Gatwick Aviation Museum with its engines in working order.

Specifications

• Crew: 10
• Length: 87 ft 4 in (26.62 m)
• Wingspan: 120 ft (37 m)
• Height: 17 ft 6 in (5.33 m)
• Empty weight: 51,400 lb (23,315 kg)
• Max takeoff weight: 86,000 lb (39,009 kg)
• Powerplant: 4 × Rolls-Royce Griffon 57 V-12 liquid-cooled piston engines, 1,960 hp (1,460 kW) each
• Maximum speed: 260 kn (300 mph, 480 km/h)
• Range: 1,950 nmi (2,240 mi, 3,610 km)
• Endurance: 14 hours 36 minutes
• Service ceiling: 20,200 ft (6,200 m)

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