Avro Lancaster

The Lancaster was a success built from the failure of the twin-engined Avro Manchester. The Manchester's airframe offered useful internal volume, but its two Rolls-Royce Vulture engines proved persistently unreliable. Avro chief designer Roy Chadwick and his team retained much of the fuselage and tail, fitted a longer wing and replaced the Vultures with four proven Rolls-Royce Merlin engines. The resulting aircraft was initially known as the Manchester III before receiving its own name.

The prototype first flew on 9 January 1941. Its combination of manageable flying qualities, four-engine reliability and an unobstructed 33 ft (10.1 m) bomb bay gave Bomber Command the heavy bomber it had urgently needed. No. 44 (Rhodesia) Squadron flew the Lancaster's first operational sortie on the night of 3–4 March 1942, laying mines in the Heligoland Bight. Its first bombing operation followed on 17 April, when twelve Lancasters of Nos. 44 and 97 Squadrons attacked the MAN diesel-engine works at Augsburg at low level; only five returned.

The Lancaster's defining structural advantage was its long bomb bay, uninterrupted by a central spar. A normal maximum bomb load was about 14,000 lb (6,350 kg), assembled from high-explosive bombs, incendiaries or large blast weapons such as the 4,000 lb ‘Cookie’. The bay's length also made the airframe unusually receptive to special weapons. It was not simply the weight carried, but the range of loads that could be arranged beneath the fuselage, that gave the Lancaster much of its operational flexibility.

That length is why the aircraft kept being handed weapons nobody had designed a bomber for. Modified Lancasters carried Barnes Wallis’s 12,000 lb Tallboy and 22,000 lb Grand Slam deep-penetration bombs; the most heavily altered B.I (Special) gave up its bomb-bay doors and some defensive equipment to take a Grand Slam externally. Each of those adaptations began as a hole in the bottom of the aeroplane that happened to be long enough.

A total of 7,377 Lancasters were built by six major manufacturers across ten factories in Britain and Canada. The B.I used British-built Rolls-Royce Merlins and the B.III was its Packard-Merlin counterpart, deliveries beginning in early 1943; Canadian production at Victory Aircraft gave the Packard-powered B.X.

The odd one out is the most revealing. The B.II was fitted with four 1,650 hp Bristol Hercules radials and delivered from September 1942, and it existed for one reason: the Merlin was the single point of failure in the entire British aero-engine programme, and a shortage would have stopped Lancaster production dead. The Hercules version was insurance against that, taken out and — as it turned out — never needed at scale.

The design outlived the campaign it was built for. Lancaster components and Chadwick’s design work fed the York transport and the Lancastrian airliner, while the enlarged Lincoln was the direct post-war development of the bomber itself.

The line then ran on further than anyone intended. The Lincoln led to the Shackleton maritime-patrol aircraft, which kept Chadwick’s four-engined ancestry in RAF service into the 1990s — half a century after the prototype first flew, and long after every other aircraft of the 1941 generation had gone.

The Lancaster's most famous operation came on the night of 16–17 May 1943. Nineteen specially modified aircraft of the newly formed No. 617 Squadron, led by Wing Commander Guy Gibson, set out from RAF Scampton to attack dams supplying the Ruhr. Barnes Wallis's cylindrical Upkeep mine had to be released at about 60 ft (18 m) and 232 mph (373 km/h), spinning backwards so that it skipped across the water, cleared protective nets and sank beside the dam wall before detonating.

The Möhne and Eder dams were breached; the Sorpe was damaged but remained standing. Eight of the nineteen Lancasters were lost, 53 of the 133 aircrew were killed and three became prisoners of war. The resulting floods killed roughly 1,300 people, including civilians, prisoners of war and forced labourers, although published totals vary. German repair work restored the dams more rapidly than British planners had expected. Gibson received the Victoria Cross, and the raid became famous, but its human cost and limited long-term industrial effect remain essential parts of the record.

Special operations were a small part of the Lancaster's service. Its principal task was the sustained night offensive against German cities, industrial regions and transport systems. A crew of seven—pilot, flight engineer, navigator, bomb aimer, wireless operator and two gunners—spent hours in an unpressurised, poorly heated aircraft before crossing defended territory. Searchlights, heavy and light anti-aircraft fire, night fighters, icing and mechanical failure could all prevent a return. The average age of a Lancaster crew was only 22.

Lancasters attacked the Ruhr, Hamburg, Berlin and many other targets as Bomber Command shifted between area attacks and more precisely defined industrial or transport objectives. Pathfinder crews marked aiming points, electronic aids improved navigation, and countermeasures attempted to confuse German radar, yet darkness, cloud and target smoke continued to scatter bomb loads. The campaign damaged German production and communications, but it also destroyed urban districts and killed civilians on a vast scale.

Sinking the Tirpitz took the Lancasters three goes across two months. On 15 September 1944, Operation Paravane, 617 Squadron under Wing Commander J. B. “Willie” Tait and 9 Squadron under Wing Commander James Bazin attacked her in Kaafjord — having first flown 38 Lancasters to Yagodnik, a Soviet naval air station near Archangel, because no British base was within reach. One Tallboy hit the bow and wrecked it.

The ship was moved south to Tromso, now within range of Scotland. Operation Obviate, on 29 October, put 38 bombers over the target and found it under cloud: no direct hit, though a near miss damaged the hull. Two weeks later, on 12 November 1944, Operation Catechism caught her in clear air. At least two Tallboys struck, others burst alongside, and the battleship capsized with the loss of about 1,000 men.

The Bielefeld viaduct carried the main rail line into the Ruhr and Bomber Command had been failing to bring it down for months. On 14 March 1945 617 Squadron went back with 28 aircraft carrying Tallboys and the first 22,000 lb Grand Slam ever dropped in anger — accounts differ over whether one or two of the big bombs went that day.

It missed the viaduct by about eighty yards, which was the point of the weapon. Grand Slam was not built to hit a structure but to go deep beside it and bring the ground out from under: eleven seconds after impact the earth opened into a crater, the piers were undermined, and the Tallboy near misses finished the span. Between 14 March and 19 April 1945 the squadron dropped 41 or 42 Grand Slams — the count varies by whether one late drop is included — against viaducts, bridges and submarine pens.

In the last fortnight the payload changed from explosives to food. The western Netherlands, still under German occupation and cut off since the previous autumn, was starving. Eisenhower agreed a local truce with Arthur Seyss-Inquart, the Reichskommissar, under which German troops would not fire on aircraft flying to marked drop zones — six of them, at Valkenburg, Duindigt, Ypenburg, Waalhaven, Kralingse Plas and Gouda.

242 Lancasters flew on the first day, 29 April 1945, dropping from a few hundred feet with the bomb doors open and no bomb sight worth using. The RAF effort ran to 3,156 flights by 300 Lancasters and 145 Mosquitos and delivered 6,685 tons; counted together with the American Chowhound the two operations flew over 5,500 sorties and dropped some 10,000 tons before the German surrender on 8 May. Lancasters then flew Operation Exodus, bringing liberated prisoners of war home.

Lancasters flew about 156,000 sorties and dropped 608,612 tons of bombs. Of the 7,377 built, 3,249 were lost on operations, and the RAF Museum records that the average Lancaster completed only 21 missions before it was lost. More than 21,000 Lancaster crew members died. Those totals expose the limits of describing the aircraft through performance figures: its reliability and carrying capacity mattered because crews had to cross one of the most heavily defended airspaces in the world, repeatedly, at night.

The Lancaster became Britain's best-known heavy bomber because it combined sound handling with a bomb bay adaptable to tasks ranging from mass night raids to attacks with Upkeep, Tallboy and Grand Slam. That technical achievement does not settle the historical argument surrounding the campaign in which it served. The aircraft can be recognised as an exceptionally effective design while the destruction of German cities, the deaths of civilians and the losses suffered by Bomber Command remain fully visible. Of the 7,377 Lancasters built, more than half were lost to enemy action or in training accidents, and 55,573 of Bomber Command’s aircrew were killed.

• 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.
• John Sweetman, David Coward & Gary Johnstone, The Dambusters (Time Warner) — and for the Tirpitz operations.