Lancaster was Britain
's most successful heavy bomber
of World War II
. Designed as a follow-on to the twin-engined Manchester
bomber, the Lancaster was originally intended to retain the same powerplant. This resulted in disappointing performance, however, and Avro replaced the twin Vulture engines of the Manchester with four Rolls-Royce Merlin
monsters, and the Lancaster first took flight in October 1941
The airplane was fairly beefy-looking, with a squared fuselage cross-section and the four massive Merlins slung under the high wing. The tail was twinned, each stabilizer placed outboard at the end of one of the tail canards; in addition to better horizontal stability and redundancy in case of damage, this afforded the dorsal gunner a much better field of fire versus following aircraft. Between the dorsal turret, the tail gunner and the early models' belly guns, a fairly withering amount of Vickers machine-gun fire could be directed aft.
This airplane is probably most famous for its use by the RAF's 617 Squadron, also known as The Dam Busters for their most famous operation. Specially modified Lancasters carrying 'skip bombs' (backspinning barrel-shaped devices) destroyed seven major German dams in the Ruhr in one night, doing horrific damage. Following that, 617 squadron (which had been created for this special op) was retained as a special duty squadron. They were the first to use the six-ton 'Tallboy' earth-penetrating bomb, as well as the eleven-ton 'Grand Slam' cratering bomb. Both were developed by Barnes Wallis, the man responsible for the Dam raid. At its peak, the Lancaster's maximum bomb load was 22,000 pounds - one 'Grand Slam' weapon, with bomb bay doors removed and fuselage strengthened to handle it. A witness to a Lancaster taking off with a Grand Slam hung underneath noted with awe that the mainspar (the main structural line of the wing) was visibly curved - the wingtips were bent up as the massive weight of the aircraft and bomb stressed their carrying capacity.
The use of Merlin engines would create production problems, since these powerful units were also used in the fighters of the day (Hurricane, Spitfire, Defiant, etc.) This led to an intermediate version of the Lancaster which used Hercules radial engines; this (the Lancaster Mk. II) had a short-lived production run due to disappointing performance and the fact that American production of Merlins picked up rapidly and could fill the gaps. Fully loaded, the Lancaster cruised at 286 knots, at a max altitude of 24,600 feet. Its combat radius was impressive; fully loaded at 22,000 lbs. the Lanc could hit targets 775 nautical miles from base, which covered all of Germany and Austria, as well as most of Czechoslovakia. With a 12,000 lb. bomb load, it could range 865 miles, to include Poland, Yugoslavia and parts of Romania; and downloaded to 7,000 lbs it had the fairly staggering radius of 1,265 nm, allowing it to hit targets in the Med.
Empty, it could remain aloft (losing altitude slowly but steadily) on one operating engine, and fly level with two; this, plus its ability to absorb fairly ridiculous amounts of airframe damage, helped many crews return to England after severe pastings by flak and/or fighters. There were a few special-duty versions made; one with no turrets but loads of electronic warfare gear designed to disrupt German electronic defenses during raids (one of the first dedicated jamming platforms, whose lineage continues today in the EA-6B intruder, EF-111 Raven and EF-4 Wild Weasel aircraft (only the first of which is still operating with the U.S. military).
Crew positions on the Lancaster (Mk.I-Mk.III) were:
On very early aircraft, there was a belly gun
position which was removed for weight/range/speed savings as the Lancaster was moved to night operations only.
For an excellent set of stories of the Lancasters and 617 squadron in action, I recommend Paul Brickhill's The Dam Busters - a great war story which was made into a so-so movie.