Avro Lancaster

Avro Lancaster
Royal Air Force Avro Lancaster B I PA474 of the Battle of Britain Memorial Flight.
RoleHeavy bomber
ManufacturerAvro
Designed byRoy Chadwick
First flight8 January 1941
Introduced1942
Retired1963 (Canada)
Primary usersRoyal Air Force
Royal Canadian Air Force
Number built7,377
Unit cost£45-50,000 when introduced
£1.3-1.5 million in 2005 currency
Developed fromAvro Manchester
VariantsAvro Lancastrian
Avro Lincoln
Avro York

The Avro Lancaster was a British four-engine Second World War heavy bomber made initially by Avro for the Royal Air Force (RAF). It first saw active service in 1942, and together with the Handley Page Halifax it was one of the main heavy bombers of the RAF, the RCAF and squadrons from other Commonwealth and European countries serving within RAF Bomber Command. The "Lanc" or "Lankie," as it was affectionately known, became the most famous and most successful of the Second World War night bombers, "delivering 608,612 tons of bombs in 156,000 sorties." Although the Lancaster was primarily a night bomber, it excelled in many other roles including daylight precision bombing, and gained worldwide renown as the "Dam Buster" used in the 1943 Operation Chastise raids on Germany's Ruhr Valley dams.

Design and development

The origins of the Lancaster lie in a twin-engined bomber design submitted to meet Specification P.13/36, which was for a new generation of twin-engined medium bombers for "worldwide use", the engine specified as the Rolls-Royce Vulture. The resulting aircraft was the Manchester, which, although a capable aircraft, was troubled by the unreliability of the Vulture. Only 200 Manchesters were built and they were withdrawn from service in 1942.

Profile of the forward section of a Lancaster, showing the FN5 turret, bomb aimer's perspex blister and the Merlin engines

Avro's chief designer, Roy Chadwick, was already working on an improved Manchester design using four of the more reliable but less powerful Rolls-Royce Merlin engines on a larger wing. The aircraft was initially designated Avro Type 683 Manchester III, and later re-named the Lancaster. The prototype aircraft BT308 was assembled by Avro's experimental flight department at Manchester's Ringway Airport from where test pilot H.A. "Bill" Thorn took the controls for its first flight on Thursday, 9 January 1941. The aircraft proved to be a great improvement on its predecessor, being "one of the few warplanes in history to be 'right' from the start." Its initial three-finned tail layout, a result of the design being adapted from the Manchester I, was quickly changed on the second prototype DG595 and subsequent production aircraft to the familiar twin-finned specification also used on the later Manchesters (below).

Some of the later orders for Manchesters were changed in favour of Lancasters; the designs were very similar and both featured the same distinctive greenhouse cockpit, turret nose and twin tail. The Lancaster discarded the stubby central third tail fin of the early Manchesters and used the wider span tailplane and larger elliptical twin fins from the later Manchester IA.

The Lancaster is a mid-wing cantilever monoplane with an oval all-metal fuselage. The wing was constructed in five main sections, the fuselage in five sections. All wing and fuselage sections were built separately and fitted with all the required equipment before final assembly. The tail unit had twin oval fins and rudders. The Lancaster was initially powered by four wing-mounted Rolls-Royce Merlin piston engines with three-bladed airscrews. It had retractable main landing gear and fixed tail-wheel, with the hydraulically operated main landing gear raised into the inner engine nacelles.

Tail-end Charlie's FN20 turret on a Canadian Lancaster

The majority of Lancasters built during the war years were manufactured by Avro at their factory at Chadderton near Oldham, Lancashire and test flown from Woodford Aerodrome in Cheshire. Other Lancasters were built by Metropolitan-Vickers (1080, also tested at Woodford) and Armstrong Whitworth. The aircraft was also produced at the Austin Motor Company works in Longbridge, Birmingham later in the Second World War and postwar by Vickers-Armstrongs at Chester. Only 300 of the Lancaster B II fitted with Bristol Hercules engines were constructed; this was a stopgap modification caused by a shortage of Merlin engines as fighter production was of higher priority. Many BIIs were lost after running out of fuel. The Lancaster B III had Packard Merlin engines but was otherwise identical to contemporary B Is, with 3,030 B IIIs built, almost all at A.V. Roe's Newton Heath factory. The B I and B III were built concurrently, and minor modifications were made to both marks as new batches were ordered. Examples of these modifications were the relocation of the pitot head from the nose to the side of the cockpit, and the change from de Havilland "needle blade" propellers to Hamilton Standard or Nash Kelvinator made "paddle blade" propellers.

Of later variants, only the Canadian-built Lancaster B X, manufactured by Victory Aircraft in Malton, Ontario, was produced in significant numbers. A total of 430 of this type were built, earlier examples differing little from their British-built predecessors, except for using Packard-built Merlin engines and American-style instrumentation and electrics. Late-series models replaced the Frazer Nash mid-upper turret with a differently configured Martin turret, mounted slightly further forward for weight balance. A total of 7,377 Lancasters of all marks were built throughout the duration of the war, each at a 1943 cost of 45-50,000 (approximately equivalent to 1.3-1.5 million in 2005 currency).

Diagram comparing the Stirling (yellow) with its contemporaries; the Avro Lancaster (blue) and the Handley Page Halifax (pink).

The test pilot, Alex Henshaw, is the only pilot known to have barrel rolled a Lancaster bomber, a feat considered almost impossible because of the slow speed of the aircraft.

Crew accommodation

In a standard Lancaster as used in the war, the crew were accommodated as follows: starting at the nose, the bomb aimer had two positions to man. His primary location was lying prone on the floor of the nose of the aircraft, where he had access to the controls for the bombsight head in front, with the bombsight computer on his left and bomb release selectors on the right. He would also use his view out of the large transparent perspex nose cupola to assist the navigator with map reading. To man the Frazer Nash FN5 nose turret, he simply had to stand up and he would be in position behind the triggers of his twin .303 in (7.7 mm) guns. The bomb aimer's position contained the nose parachute exit in the floor.

Moving backwards, on the roof of the bomb bay the pilot and flight engineer sat side-by-side under the expansive canopy, with the pilot sitting on the left on a raised portion of the floor. The flight engineer sat on a collapsible seat (known as a "second dicky seat") to the pilot's right, with the fuel selectors and gauges on a panel behind him and to his right.

Behind these crew members, and behind a curtain fitted to allow him to use light to work, sat the navigator. His position had him facing to port with a large chart table in front of him. An instrument panel showing the airspeed, altitude and other details required for navigation was mounted on the side of the fuselage above the chart table.

The radios for the wireless operator were mounted on the left-hand end of the chart table, facing towards the rear of the aircraft. Behind these radios, facing forwards, on a seat at the front of the main spar sat the wireless operator. To his left was a window, and above him was the astrodome, used for visual signalling and also by the navigator for celestial navigation.

Behind the wireless operator were the two spars for the wing, which created a major obstacle for crew members moving down the fuselage even on the ground. On reaching the end of the bomb bay the floor dropped down to the bottom of the fuselage, and the mid upper gunner's Frazer Nash FN50 or FN150 turret was reached. His position allowed a 360 view over the top of the aircraft, with two .303 in (7.7 mm) Browning machine guns to protect the aircraft from above and to the side. The mid-upper gunner had perhaps the most uncomfortable ride of all the crew, as he was seated on a rectangle of canvas that was slung beneath the turret once the gunner had occupied his position. He could be required to occupy this seat for up to eight hours at a time.

To the rear of the turret was the side crew door, on the starboard side of the fuselage. This was the main entrance to the aircraft, and also could be used as a parachute exit. At the extreme rear of the aircraft, over the spars for the tailplane, the rear gunner sat in his exposed position in the FN20, FN120 or Rose Rice turret. In the FN20 and FN120 turrets, he had four .303 in (7.7 mm) Brownings, and in the Rose Rice turret he had two .50 in (12.7 mm) Brownings. Neither the mid upper or rear gunner's positions were heated, and the gunners had to wear electrically heated suits to prevent hypothermia and frostbite. Many rear gunners insisted on having the centre section of perspex removed from the turret to give a completely unobstructed view.