Avro 683 “Lancaster” B.Mk.I “Special”
Archive Photos Airplane Trading Cards and Photos [2,3,4,5]
[Avro 683 Lancaster Mk.I Special (PD120, YZ-R), Airplane card: 1993 “World War II War Machines, the Flight Series”, The Rogers Group, USA (The Skytamer Archive)]
Avro 683 Lancaster
The Lancaster owes its origin to Air Ministry specification B.13/36 for a twin-engined medium bomber to be fitted with Rolls-Royce Vulture engines. The first aircraft built to this specification was the Manchester, the prototype of which first flew in July, 1939. About 18 months later the Manchester began to go into squadron service in the RAF.
Owing to delays in the development of the Vulture engine the decision was taken in mid-1940 to design a new version of the Manchester to be fitted with four Rolls-Royce Merlin engines. The first conversion made use of about 75% of parts and assemblies of the Manchester, the principal change being the provision of a new center-section with mountings for four Merlin × engines. This aeroplane became the first prototype of the Lancaster.
A second prototype fitted with four Merlin XX engines and considerably modified in detail was designed, built and flown in some eight months.
The first production Lancasters began to come off the production lines early in 1942 and in the same year the decision was made to produce the Lancaster in Canada. The first Canadian-built Lancaster was delivered by air across the Atlantic in September, 1943. In 1944 Lancaster production was begun in Australia.
The Lancaster is the most versatile of British heavy bombers. It can carry a maximum internal load of 18,000 lbs without modification to the standard bomb-bay. On a range of 1,000 miles its normal load is 14,000 lbs. With modifications to the bomb-bay it carries both the 12,000 lb and 22,000 lb bombs, the only bomber in the World to carry bombs of these sizes.
There have been four basic versions of the Lancaster. These are as follow:
The Avro Lancaster 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 stem from 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.
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.
Some of the later orders for Manchesters were changed in favor 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 Mk.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.
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 B.IIs 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.Mk.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 £s;45-50,000 (approximately equivalent to £s;1.3-1.5 million in 2005 currency).
Crew Accommodation 
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, with 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 faced 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, entered through a small hatch in the rear of the fuselage, and depending on the size of the rear gunner, the area was so cramped that the gunner would often hang their parachute on a hook inside the fuselage, near the turret doors. 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 center section of perspex removed from the turret to give a completely unobstructed view.
While eight .303 in (7.7 mm) machine guns were the most common Lancaster armament, twin .50 in (12.7 mm) turrets were later available in both the tail and dorsal positions. A Preston-Green mount was available for a .50 in (12.7 mm) mounted in a ventral blister, but this was mostly used in RCAF service. This blister was later the location for the H2S radar. A Nash & Thomson FN-64 periscope-sighted twin .303 in (7.7 mm) ventral turret was also available but rarely fitted as it was hard to sight. (Similar problems afflicted the ventral turret in the North American B-25C Mitchell and other bombers). Some unofficial mounts for .50 in (12.7 mm) machine guns or even 20 mm cannon were made, firing through ventral holes of various designs.
An important feature of the Lancaster was its extensive bomb bay, at 33 ft (10.05 m) long. Initially, the heaviest bombs carried were 4,000 lb (1,820 kg) “Cookies ”. Bulged doors were added to allow the aircraft to carry 8,000 lb (3,600 kg) and later 12,000 lb (5,450 kg) “Cookies”. Towards the end of the war, attacking special and hardened targets, the B.I Specials could carry the 21 ft (6.4 m) long 12,000 lb (5,450 kg) “Tallboy” or 25.5 ft (7.77 m) long 22,000 lb (9,980 kg) “Grand Slam” “earthquake” bombs, the Lancaster was able to deliver the heaviest bombs made. To carry the “Grand Slam” extensive modifications to the aircraft were required which led to them being redesignated as B.I (Specials). The modifications included removal of the mid-upper turret, two guns from the rear turret, removal of all of the cockpit armor plating and installation of Rolls-Royce Merlin Mk.24 Engines which had better take-off performance. The bomb-bay doors were removed and the rear end of the bomb bay cut away to clear the tail of the bomb. Later the nose turret was also removed to further improve performance.
Bombsights used on Lancasters included:
Radio, Radar and Countermeasures Equipment 
The Lancaster had a very advanced communications system for its time. Most British-built Lancasters were fitted with the R1155 receiver and T1154 transmitter, whereas the Canadian built aircraft and those built for service in the Far East had American radios. These provided radio direction-finding, as well as voice and Morse capabilities.
Operational History 
Lancasters flew 156,000 sorties and dropped 608,612 long tons (618,378 tonnes) of bombs between 1942 and 1945. Lancs took part in the devastating round-the-clock raids on Hamburg during Air Marshall Harris' “Operation Gomorrah” in July 1943. Just 35 Lancasters completed more than 100 successful operations each, and 3,249 were lost in action. The most successful survivor completed 139 operations, and was scrapped in 1947.
A famous Lancaster bombing raid was the 1943 mission, codenamed “Operation Chastise”, to destroy the dams of the Ruhr Valley. The mission was carried out by 617 Squadron in modified Mk.IIIs carrying special drum shaped bouncing bombs designed by Barnes Wallis. The story of the mission was later made into a film, “The Dam Busters.” Also famous was a series of Lancaster attacks using “Tallboy” bombs against the German battleship Tirpitz, which first disabled and later sank the ship.
Lancasters from Bomber Command were to have formed the main strength of Tiger Force, the Commonwealth bomber contingent scheduled to take part in Operation Downfall, the codename for the planned invasion of Japan in late 1945, from bases on Okinawa.
RAF Lancasters dropped food into the Holland region of the occupied Netherlands, with the acquiescence of the occupying German forces, to feed people who were in danger of starvation. Named after the food Manna which miraculously appeared for the Israelites in the Book of Exodus, the aircraft involved were from 1, 3 and 8 Groups, and consisted of 145 Mosquitoes and 3,156 Lancasters, flying between them a total of 3,298 sorties. The first of the two RAF Lancasters chosen for the test flight was nicknamed “Bad Penny” from the old expression: “a bad penny always turns up.” This bomber, with a crew of seven men (five Canadians including pilot Robert Upcott of Windsor, Ontario), took off in bad weather on the morning of 29 April 1945 without a cease fire agreement from the German forces, and successfully dropped her cargo.
A development of the Lancaster was the Avro Lincoln bomber, initially known as the Lancaster IV and Lancaster V. These two marks became the Lincoln B1 and B2 respectively. There was also a civilian airliner based on the Lancaster, the Lancastrian. Other developments were the York, a square-bodied transport and, via the Lincoln, the Shackleton which continued in airborne early warning service up to 1992.
In 1946, four Lancasters were converted by Avro at Bracebridge Heath, Lincolnshire as freighters for use by British South American Airways, but proved to be uneconomical and were withdrawn after a year in service.
Four Lancaster Mk.III's were converted by Flight Refuelling Limited as two pairs of tanker and receiver aircraft for development of in-flight refueling. In 1947, one aircraft was flown non-stop 3,459 mi (5,567 km) from London to Bermuda. Later the two tanker aircraft were joined by another converted Lancaster and were used in the Berlin Airlift, achieving 757 tanker sorties.
Fifty-nine Lancaster B.Is and B.VIIs were overhauled by Avro at Woodford and Langar and delivered to the Aeronavale (France) during 1952/53. These were flown until the mid-1960s by four squadrons in France and New Caledonia in the maritime reconnaissance and search-and-rescue roles. During its Argentinian service, Lancasters saw limited use in military coups, owing to the small number there.
Avro Lancaster B.I — The original Lancasters were produced with Rolls-Royce Merlin XX engines and SU carburetors. Minor details were changed throughout the production series - for example the pitot head design was changed from being on a long mast at the front of the nose to a short fairing mounted on the side of the fuselage under the cockpit. Later production Lancasters had Merlin 22 and 24 engines. No designation change was made to denote these alterations.
Avro Lancaster B.I Special — Adapted to take first the super-heavy “Tallboy” and then “Grand Slam” bombs. Upgraded engines with paddle-bladed propellers gave more power, and the removal of gun turrets reduced weight and gave smoother lines. For the Tallboy, the bomb-bay doors were bulged; for the Grand Slam, they were removed completely and the area faired over. For some Tallboy raids, the mid upper turret was removed. This modification was retained for the Grand Slam aircraft, and in addition the nose turret was later removed. Two airframes (HK541 and SW244) were modified to carry a dorsal “saddle tank” with 1,200 gal (5,455 L) mounted aft of a modified canopy for increasing range. No. 1577 SD Flight tested the aircraft in India and Australia in 1945 for possible use in the Pacific, but the tank adversely affected handling characteristics when full and flight refueling was later used instead.
Avro Lancaster PR.I — B.1 modified for photographic reconnaissance, operated by RAF No. 82 and No. 541 Squadrons, wartime. All armament and turrets were removed with a reconfigured nose and a camera carried in the bomb bay. The type was also operated by 683 Squadron from circa 1950 for photographic reconnaissance based at Aden and subsequently Habbaniya in Iraq until disbanded 30 November 1953.
Avro Lancaster B.I (FE) — In anticipation of the needs of the Tiger Force operations against the Japanese in the Far East (FE), a tropicalized variant was based on late production aircraft. The B I (FE) had modified radio, radar, navaids and a 400 gal (1,818 L) tank installed in the bomb bay. The mid-upper turret was also removed.
Avro Lancaster B.II — Bristol Hercules (Hercules VI or XVI engines) powered variant, of which 300 were produced by Armstrong Whitworth. One difference between the two engine versions was that the VI had manual mixture control, requiring an extra lever on the throttle pedestal. These aircraft were almost always fitted with an FN.64 ventral turret and pronounced step in the bulged bomb bay.
Avro Lancaster B.Mk.III — These aircraft were fitted with Packard-built Merlin engines and produced at the same time as the B.I, the two marks being indistinguishable externally. The minor differences between the two variants were related to the engine installation, and included the addition of slow-running cut-off switches in the cockpit, a requirement due to the Bendix Stromberg pressure-injection carburetors fitted to the Packard Merlin engines.
Avro Lancaster B.III Special — Known at the time of modification as the “Type 464 Provisioning” Lancaster, this variant was built to carry the "Upkeep" bouncing bomb for the dam busting raids. The bomb-bay doors were removed and Vickers-built struts to carry the bomb were fitted in their place. A hydraulic motor, driven by the pump previously used for the mid upper turret was fitted to spin the bomb. Lamps were fitted in the bomb bay and nose for the simple height measurement system which enabled the accurate control of low-flying altitude at night. The mid-upper turret was removed to save weight, and the gunner moved to the front turret to relieve the bomb aimer from having to man the front guns so that he could assist with map reading.
Avro Lancaster ASR.III/ASR.3 — B.III modified for air-sea rescue, with three dipole ventral antennas fitted aft of the radome and carrying an airborne lifeboat in the re-configured bomb bay. The armament was often removed and the mid-upper turret faired-over, especially in postwar use. Observation windows were added to both sides of the rear fuselage, a port window just forward of the tailplane, and a starboard window into the rear access door. A number of ASR.3 conversions were fitted with Lincoln-style rudders.
Avro Lancaster GR.3/MR.3 — B.III modified for maritime reconnaissance.
Avro Lancaster B.IV — The B.IV featured an increased wingspan and lengthened fuselage and new Boulton Paul F turret (two × 0.5 in) with re-configured framed “bay window” nose glazing. The prototypes (PW925, PW929 and PW932) were powered by two-stage Merlin 85s inboard and later, Merlin 68s on the outboard mounts. Because of the major re-design, the aircraft was quickly renamed Lincoln B.1.
Avro Lancaster B.V — Increased wingspan and lengthened fuselage, two-stage Merlin 85s. Renamed Lincoln B.2.
Avro Lancaster B.VI — Nine aircraft converted from B.IIIs. Fitted with Merlin 85/87 which had two-stage superchargers, giving much improved high altitude performance. The Merlin 85/87 series engines were fitted with annular cowlings similar to the post war Avro Lincoln and four bladed paddle-type propellers were fitted. These aircraft were only used by Pathfinder units; by No. 7 Squadron RAF, No. 83 Squadron RAF, No. 405 Squadron RCAF and by No. 635 Squadron RAF. Often used as a "Master Bomber" the B.VIs allocated to RAF Bomber Command (2 being retained by Rolls Royce for installation and flight testing) had their dorsal and nose turrets removed and faired-over. The more powerful engines proved troublesome in service and were disliked by ground maintenance staff for their rough running and propensity to 'surge and hunt', making synchronization impossible. The B.VI was withdrawn from service in November 1944 and the surviving aircraft were used by Rolls Royce, the Royal Aircraft Establishment and the Bomb Ballistics Unit (BBU) for various testing and experimental duties.
Avro Lancaster B.VII — The B.VII was the final production version of the Lancaster. The Martin 250CE mid-upper turret was re-positioned slightly further forward than on previous Marks, and the Nash & Thomson FN-82 tail turret with twin 0.50 in (12.7 mm) Browning machine guns replaced the FN.20 turret with four 0.303 in (7.7 mm) Browning machine guns.
Avro Lancaster B.X — The B.X was a Canadian-built B.III with Canadian- and US-made instrumentation and electrics. On later batches the heavier Martin 250CE was substituted for the Nash & Thomson FN-50 mid-upper turret, mounted further forward to maintain center of gravity balance. Canada was a long term operator of the Lancaster, utilizing modified aircraft in postwar maritime patrol, search and rescue and photo-reconnaissance roles until 1964. The last flight by the RCAF was flown by F/L Lynn Garrison in KB-976, on 4 July 1964 at the Calgary International Air Show.
Surviving Aircraft 
Avro 683 Lancaster B.Mk.I Specifications [6,7]
Tail Unit 
Landing Gear 
Power Plant [6,7]
Armament, Bombs, Armor and Equipment 
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