Avro 696 “Shackleton M.R.Mk.2”
British Four-engine Maritime Patrol Aircraft
[Avro 696 Shackleton M.R.2 (WG531), Airplane card: 1953 “British Planes” Morning Foods Ltd., Mornflake Quick Cooking Oats, England, UK (The Skytamer Archive)]
Avro 696 Shackleton
- Role: Maritime patrol aircraft
- Manufacturer: Avro
- First flight: March 1949
- Introduced: April 1951
- Retired: 1990
- Primary users: Royal Air Force, South African Air Force
- Produced: 1951-1958
- Number built: 185
- Developed from: Avro Lincoln
The Avro Shackleton was a British long-range maritime patrol aircraft for use by the Royal Air Force. It was developed by Avro from the Avro Lincoln bomber with a new fuselage. It was originally used primarily in the anti-submarine warfare (ASW) and maritime patrol aircraft (MPA) roles, and was later adapted for airborne early warning (AEW), search and rescue (SAR) and other roles from 1951 until 1990. It also served in the South African Air Force from 1957 to 1984. The type is named after the polar explorer Sir Ernest Shackleton.
Design and Development
The aircraft was designed by Roy Chadwick as the Avro Type 696. It was based on the Lincoln, itself a derivative of the successful wartime Lancaster heavy bomber, one of Chadwick's earlier designs which was the then current ASW aircraft. The design took the Lincoln's wings and landing gear and mated them with a new fuselage, and was initially referred to during development as the Lincoln ASR.3. The engines were Rolls-Royce Griffons with 13 ft (4 m) diameter contra-rotating propellers, creating a distinctive engine noise and adding high-tone deafness to the hazards of the pilots. The first test flight was in March 1949 and front-line aircraft were delivered to Coastal Command in April 1951 and had their operational debut during the Suez Crisis. In the ASW role, the Shackleton carried both types of sonobuoy, ESM, an Autolycus (diesel fume detection system) and for a short time an unreliable magnetic anomaly detector (MAD) system. Weapons were nine bombs, or three torpedoes or depth-charges, and 20 mm cannon.
The M.R.2 was improved with feedback from operations and is considered by aficionados to be the definitive type. The radome was moved from the nose to a ventral position, to improve all-round coverage and minimize the risk of bird-strikes. Both the nose and tail sections were lengthened, the tailplanes were redesigned and the undercarriage was strengthened.
The M.R.3 was another redesign in response to crew complaints. A new tricycle undercarriage was introduced, the fuselage was increased in all main dimensions and had new wings with better ailerons and tip tanks. As a sop to the crews, on fifteen hour flights the sound deadening was improved and a proper galley and sleeping space were included. Total take-off weight had risen by over 30,000 lb (13,600 kg) (Ph. III) and assistance from Armstrong Siddeley Viper Mk.203 turbojets was needed on take-off (JATO). This extra strain took a toll on the airframe, and flight life of the Mk.III's was sufficiently reduced that they were outlived by the Mk.IIs.
A total of 185 Shackletons were built from 1951 to 1958: around twelve are still believed to be intact, with one still flying (SAAF 1722 based at AFB Ysterplaat).
Royal Air Force
All marks suffered from using the Griffon engines - thirsty for fuel and oil, noisy and temperamental with high-maintenance needs. In 1961, M.R.2s engines needed top overhauls every 400 hours and went through a spate of ejecting spark plugs from their cylinder heads. It was not unusual to see an engine changed every day in a unit of six aircraft. They were constantly on the cusp of being replaced, but the potentially beneficial Napier Nomad re-engine did not happen.
The need to replace the Shackleton was first raised in the early 1960s. The arrival of the Hawker-Siddeley Nimrod in 1969 was the end for the Shackleton in most roles but it continued as the main SAR aircraft until 1972. The intention to retire the aircraft was then thwarted by the need for AEW coverage in the North Sea and northern Atlantic following the retirement of the Fairey Gannet. With a new design not due until the late 1970s the existing AN/APS-20 radar was installed in Mk.IIs as an interim measure, the A.E.W.2, from 1972. The Nimrod AEW replacement program dragged on and the eventual successor to the Shackleton did not arrive until the RAF finally abandoned the Nimrod AEW and purchased the Boeing E-3 Sentry in 1991.
South African Air Force
After evaluating four RAF M.R.2s in 1953, the South African Air Force ordered 8 aircraft to replace the Short Sunderland in maritime patrol duties. Some minor modifications were required for South African conditions and the resulting aircraft became the Mk.3 These Shackletons remained in maritime patrol service with 35 Squadron SAAF up to November 1984. The aircraft received SAAF designations 1716 to 1723. Although the joke has been applied to several aircraft, the Shackleton has been described as "a hundred thousand rivets flying in close formation."
- Shackleton G.R.1 — The first production model for the RAF, later redesignated Shackleton M.R.1
- Shackleton M.R.1A — Version powered by four Griffon 57A V12 piston engines, equipped with a chin mount radome. In service from April 1951.
- Shackleton M.R.2 — More powerfully armed and cleaner version of Mk.1. New nose with two additional 20 mm cannon aimed by gunner who sits above bomb-aimer. Fixed under-nose radome of Mk.1 deleted and replaced in Mk.2 by retractable radome, located under fuselage aft of bomb-bay. Rear fuselage faired off with transparent terminal cone to provide look-out position. Single fixed tail wheel of Mk.1 replaced by twin retractable wheels. The Mk.2 prototype flew for the first time On June 17, 1952.
- Shackleton M.R.2C — Number of Shackleton M.R.2s, fitted with the navigation and offensive equipment of the Shackleton M.R.3
- Shackleton M.R.3 — Maritime reconnaissance, anti-shipping aircraft. Developed version of Mk. 2. First production Mk.3 (WR970) flew on September 2, 1955. Nose-wheel landing-gear; increased fuel capacity, incorporating wing-tip tanks; new clear-view cockpit canopy; internal changes for increased crew comfort, etc. The tail wheel was replaced by a tricycle undercarriage configuration. In production for Royal Air Force and South African Air Force. Eight exported to South Africa.
- Shackleton M.R.3 Phase 2 — Similar to Shackleton MR.3 but fitted with two Viper turbojet engines for assisted take off.
- Shackleton M.R.4 — Project of new maritime reconnaissance version, none built.
- Shackleton A.E.W.2 — Airborne early warning aircraft. M.R.2s converted to take ex-Fairey Gannet airborne early warning radar.
- Shackleton T.4 — Navigation trainer conversion.
- South Africa: South African Air Force
- United Kingdom: Royal Air Force
- SAAF 1722 is the only remaining flying Shackleton. The aircraft is owned and operated by the South African Air Force Museum based at AFB Ysterplaat. It was one of eight Shackletons operated by the South African Air Force from 1957 to 1984, and is currently used only for occasional flight demonstrations.
- Shackleton M.R.2C (WL795) is on display at RAF St. Mawgan, England.
- Shackleton A.E.W.2 (WR960) is on display at the Museum of Science and Industry in Manchester, England.
- Shackleton A.E.W.2 (WR963) is owned by Air Atlantique Classic Flight, Coventry, England.
- Shackleton M.R.3 (WR971) is on display at the Fenland & West Norfolk Aviation Museum, Wisbech, England.
- Shackleton M.R.3 (WR974) is on display at the Gatwick Aviation Museum, England.
- Shackleton M.R.3 (WR977) is on display at the Newark Air Museum, England.
- Shackleton M.R.3 (WR982) is on display at the Gatwick Aviation Museum, England.
- Shackleton M.R.3 (WR985) is privately owned at Long Marston, England.
- Shackleton A.E.W.2 (WL747) stands abandoned at the western end of RWY 11/29 at Paphos Airport, Cyprus.
- Shackleton A.E.W.2 (WL790) is on display at the Pima Air & Space Museum, Tucson Arizona USA
- SAAF Shackleton 1716 ('Pelican 16') was restored to flight in 1994, but later that year, while on its way to the UK, it crash landed in the Sahara desert after a double engine failure. The crash did not result in any casualties, but the aircraft was abandoned in the desert.
- SAAF Shackleton 1717 is on static display at the Transport museum in Stanger.
- SAAF Shackleton 1720 is on static display at AFB Ysterplaat.
- SAAF Shackleton 1721 is on static display at the South African Air Force Museum in Swartkop.
- SAAF Shackleton 1723 is on static display at the Vic's Viking Garage, next to the N1 highway in Soweto, Johannesburg.
Avro 696 Shackleton M.R.3 Specifications
- Four-engined long-range Maritime Reconnaissance monoplane.
- Cantilever mid-wing monoplane.
- Wing root Aerofoil NACA 23018.
- Incidence 4°.
- Dihedral on outer planes (true) 4°.
- Two-spar all-metal structure.
- Hydraulically-operated split training-edge flaps, two between fuselage and inner nacelles, and two outboard of inner nacelles.
- Total flap area: 187.3 ft²
- Ailerons in outer wing panels, with trim and balance tabs in each.
- Total aileron area: 113.4 ft²
- Gross wing area: 1,421 ft²
- T.K.S. porous-metal leading-edge de-icing.
- Light-alloy stressed skin semi-monocoque structure.
- Cantilever monoplane tail and end-plate fins and rudders.
- All-metal structure.
- Total tailplane area: 285.4 ft².
- Elevator area (including tabs): 87.30 ft².
- Trim-tab area (two): 3.56 ft².
- Balance tab area (two): 3.54 ft².
- Total vertical tail area: 223 ft².
- Total rudder area (including combined balance/trim tabs): 100.2 ft².
- T.K.S. porous-metal leading-edge de-icing.
- Retractable nose-wheel type.
- Main wheels each carried between two oleo-pneumatic shock-absorbing legs, retract backward hydraulically into inner engine nacelles.
- Four 2,450-hp Rolls-Royce Griffon 67 twelve-cylinder Vee liquid-cooled engines.
- Each engine driving a de Havilland six-blade co-axial counter-rotating constant speed fully-feathering airscrew.
- Diameter of airscrew: 13 ft.
- Crew of ten.
- Pilot's compartment in forward fuselage section, seating two side-by-side.
- Other crew positions in nose and fuselage.
- Two 20 mm cannon in Bristol B.17 dorsal turret.
- Large single bomb compartment can accommodate variety of anti-shipping weapons in many combinations.
- Equipment includes extensive radio and radar, provision for carrying A/S.R. lifeboat, etc.
- Span: 119 ft. 10 in.
- Length: 92 ft 6 in.
- Height: 23 ft. 4 in.
- Wing Area: 1,321 ft²
- Tare weight: 57,800 lbs
- All-up weight: 100,000 lbs
- Maximum speed: 302 mph
- Cruising speed: 260 mph
- Initial climb rate: 850 ft/min
- Ceiling: 19,200 ft
- Range: 4,215 miles
- Morning Foods Ltd., “British Planes”, Airplane Trade Cards, 1952, R707-4, USA.
- Wikipedia. Avro Shackleton.
- Bridgman, Leonard. “Avro: The Avro Type 696 Shackleton: Shackleton M.R.Mk.3”. Jane's All the World's Aircraft 1954-55. The McGraw-Hill Book Company, Inc., New York, 1955. pp. 48-50.
- Jackson, A.J. “Avro 696 Shackleton”, Avro Aircraft Since 1908 (3rd edition). London: Putnam Aeronautical Books, London, 2000. pp. 415-421, ISBN 0-85177-797-X.
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