In 1938 the German Air Ministry called for a multi-range heavy bomber suited for anti-shipping opperations, much like the Focke Wulf Fw 200.
Heinkel's design featured many advanced proposals, including coupled engines-two mounted side by side, and driving a single propeller shaft-and remote controlled gun positions. The latter notion was soon abandoned in favor of manned turrets, and this and other heavier structural alterations (arising from attemps to stress the huge aircraft for a dive bomber) made considerable inroads upon the He 177's original optimistic performance estimates.The He 177 could carry the Fritz-X guided bomb, which it used against shipping quite effectively.
The idea and design work behind the He 177 were good, but there the merits ended. Troublesome in the extreme, and heartily disliked by its crews, it was pushed into operational service before half its worse vices had been overcome. The first prototype, powered by two 2,600hp DB 606 (coupled DB 601) engines, made its maiden flight in November of 1939 and was soon in trouble from engine heating; the second and fourth prototypes broke up in the air; the engines of the fifth prototype caught fire in flight and the aircraft crashed; and similar troubles with later prototypes rapidly, though justifiably, earned the He 177 the unwelcome nickname of "Flaming Coffin".
Yet, despite its untrustworthy powerplants and other shortcomings, work proceeded on the pre-production 177A-0 and production 177As. Recommended engine modifications, which would probably have solved many of the aircraft's initial problems, were unaccountably ignored until several hundred aircraft had been completed and put into service, by which time mare had been lost due to engine fires than in combat. The twin-finned He 177B-5 entered priority production in May 1944, but two month later this production was stopped and the few B series aircraft completed never saw service. Altogether, over 1000 He 177s of all variations were built.
Aircraft of World War II by Kenneth Munson, published by Ian Allan LTD