page_title: Avro Lancaster
section_title: Variants
hierarchical_section_title: Avro Lancaster / Variants
caption_attribution_description: English: Avro Lincoln
context_page_description: The Avro Lancaster is a British Second World War heavy bomber. It was designed and manufactured by Avro as a contemporary of the Handley Page Halifax, both bombers having been developed to the same specification, as well as the Short Stirling, all three aircraft being four-engined heavy bombers adopted by the Royal Air Force during the same wartime era.
  The Lancaster has its origins in the twin-engine Avro Manchester which had been developed during the late 1930s in response to the Air Ministry Specification P.13/36 for a capable medium bomber for "world-wide use". Originally developed as an evolution of the Manchester, the Lancaster was designed by Roy Chadwick and powered by four Rolls-Royce Merlins and in one version, Bristol Hercules engines. It first saw service with RAF Bomber Command in 1942 and as the strategic bombing offensive over Europe gathered momentum, it was the main aircraft for the night-time bombing campaigns that followed. As increasing numbers of the type were produced, it became the principal heavy bomber used by the RAF, the RCAF and squadrons from other Commonwealth and European countries serving within the RAF, overshadowing the Halifax and Stirling.
context_section_description: B.I
  The original Lancasters were produced with Rolls-Royce Merlin XX engines and SU carburettors. 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.
  B.I Special
  32 Aircraft were adapted to take first the super-heavy "Tallboy" and then "Grand Slam" bombs. Up-rated 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 an early type of in-flight refuelling designed in the late 1930s for commercial flying boats was later used instead.
  PR.1
  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(PR) Squadron when it was re-formed in November 1950 to undertake photographic reconnaissance and mapping activities, initially based at RAF Fayid, Egypt, before moving to RAF Kabrit in February 1951, and subsequently Habbaniya in Iraq until the squadron was disbanded on 30 November 1953.
  B.I (FE)
  In anticipation of the needs of the Tiger Force operations against the Japanese in the Far East (FE), a tropicalised 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. Most were painted with white upper-surfaces to reduce internal temperatures in the tropical sun, and black undersides with a low demarcation between the colours, completely omitting any red colours on the national insignia in all cases to avoid confusion with the hinomaru insignia of the Japanese.
  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. Very early examples were fitted with an FN.64 ventral turret; however, these were quickly removed due to problems with aiming the turret through its periscope (which prevented the gunner from seeing a target he was not already aiming at), and inadequate traverse speed.
  Due to the Luftwaffe Schräge Musik attacks, a variety of unofficial field modifications were made, including fitting of 20 mm cannon or a .50 inch machine gun in the open hole where the FN.64 had been installed, before an official modification (Mod 925) fitted with a .303 inch machine gun was authorised for the same location, though not in all aircraft. These were rarely installed on other variants as the H2S radar that was not used on the B II was mounted there. Three types of bulged bomb bay were used on the B II, the prototype having a narrow bulge running from just aft of the cockpit to the end of the bomb bay, while early production examples had a full width bulge that ran the same length and on late production examples the bomb bay doors were prominently bulged throughout their length.
  B.III
  This variant, which was built concurrently with the B I and was indistinguishable externally from that variant, was fitted with Packard-built Merlin engines. The Packard Merlins used Bendix – Stromberg pressure-inject
caption: Sole Canadian Lancaster B.XV/Lincoln B.XV
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