Avro Lancaster

The Lancaster was a triumph born of failure. Its direct ancestor, the twin-engined Avro Manchester, was a sound airframe crippled by its unreliable Rolls-Royce Vulture engines, and it proved a costly disappointment in service. Rather than abandon the design, Avro's chief designer Roy Chadwick grafted a new, longer wing carrying four proven Rolls-Royce Merlins onto the basic Manchester fuselage.

The transformation was complete. The new bomber, first flown on 9 January 1941, inherited the Manchester's vast, unobstructed 33-foot bomb bay but now had the power and reliability to use it. Honest to handle and free of vice, it was everything its predecessor had failed to be, and it entered squadron service early in 1942 as the most capable heavy bomber Britain would field.

The Lancaster's defining feature was that long, unbroken bomb bay, which let it carry a heavier and more varied load than any other European bomber of the war. As the Allied bombs grew larger, the Lancaster simply swallowed them — from a normal mix of incendiaries and high explosive to the 5,400 kg Tallboy and the colossal 10,000 kg Grand Slam earthquake bombs that no other aircraft could lift.

That adaptability invited special modification. For the 1943 dams raid, aircraft of No. 617 Squadron were specially rebuilt — the mid-upper turret removed and a spinning release gear fitted — to carry Barnes Wallis's bouncing bomb. Other variants experimented with different engines and, post-war, with maritime-reconnaissance equipment, but it was the standard Merlin-powered night bomber that carried the campaign.

Around 7,400 Lancasters were built. The principal production versions differed chiefly in their engines: the standard B.I and the B.III used Packard-built Merlins, while the B.II — a hedge against a feared Merlin shortage — was powered by Bristol Hercules radials. The specialised dams-raid aircraft were designated B.III (Special), and others were modified to carry the heavy Tallboy and Grand Slam bombs.

The airframe outlived the war by decades in developed forms. It led directly to the Lincoln bomber, the York transport and the Lancastrian airliner, and to the long-serving Shackleton maritime-patrol aircraft, which kept the basic lineage flying with the RAF into the 1990s — half a century after Chadwick first drew the Manchester.

The Lancaster's most famous single operation came on the night of 16–17 May 1943. Nineteen aircraft of the newly formed No. 617 Squadron, led by Wing Commander Guy Gibson, flew at treetop height across occupied Europe to attack the dams of the Ruhr industrial region with Barnes Wallis's “Upkeep” bouncing bomb — a drum-shaped charge spun backwards and released at precisely 60 feet and 232 mph to skip over the torpedo nets and sink against the dam wall.

The raid breached the Möhne and Eder dams, sending walls of water down the valleys, though the Sorpe held. It cost eight of the nineteen Lancasters and 53 of 133 aircrew killed, and the flooding drowned perhaps 1,300 people, many of them Allied prisoners and forced labourers in the valleys below. Gibson received the Victoria Cross, and “the Dam Busters” passed permanently into legend — the sharpest example of the precision role that ran alongside the Lancaster's main career as an area bomber.

Beyond such set-piece raids, the Lancaster bore the weight of Bomber Command's night offensive against the cities and industry of Germany, dropping the majority of the force's total tonnage. Flown by a crew of seven under cover of darkness, it pressed through flak and night-fighters to the Ruhr, Hamburg, Berlin and beyond, in the long and bitterly costly campaign that ran to the last weeks of the war.

It also flew many of the war's other celebrated heavy-bomber operations: the sinking of the battleship Tirpitz with Tallboy bombs, and the smashing of V-weapon sites and U-boat pens with Tallboy and Grand Slam. In its final missions it switched from destruction to mercy, dropping food to a starving occupied Holland in Operation Manna and flying home liberated prisoners of war.

Lancasters flew about 156,000 sorties and dropped 608,612 long tons of bombs — well over half of Bomber Command’s wartime total. The cost was proportionate: 3,249 Lancasters were lost on operations, around 44% of the 7,377 built, and a Lancaster crewman’s statistical chance of surviving a 30-operation tour at the height of the battle was roughly one in two.

The aircraft’s place in the mythology of the campaign is marked by valour as much as tonnage: ten Victoria Crosses were awarded to men flying Lancasters, from Guy Gibson over the Ruhr dams to Andrew Mynarski, who died trying to free his trapped rear gunner from a burning aircraft over Cambrai in June 1944.

The Avro Lancaster was the finest heavy bomber operated by RAF Bomber Command and the mainstay of Britain's war in the night sky over Germany. Reliable, capacious and beloved by its crews, it became the most celebrated British bomber of the war and the enduring image of the strategic air offensive.

Yet its story cannot be told without its cost. Bomber Command lost more than 55,000 aircrew killed — a casualty rate among the highest of any Allied force — and the area-bombing campaign it waged remains among the most debated of the war. The Lancaster carried both that courage and that controversy, a magnificent machine forever bound to the terrible arithmetic of the night offensive.

• Leo McKinstry, Lancaster: The Second World War’s Greatest Bomber (John Murray, 2009).
• Max Hastings, Bomber Command (Michael Joseph, 1979).
• Jonathan Falconer, Avro Lancaster (Haynes Manual).
• Bruce Robertson, Lancaster: The Story of a Famous Bomber (Harleyford).
• John Sweetman, The Dambusters Raid (Cassell) — Operation Chastise in detail.