The new designs would be a direct successor to the Schnellbomber philosophy of the Dornier Do 17 and Junkers Ju 88, relying on high speed as its primary defence.

Bomber B would be a much larger and more capable aircraft, with range and payload far greater than the Schnellbomber, surpassing the largest conventional designs then under consideration.

[citation needed] The first specialist bomber aircraft was the Junkers Ju 88, which had limited range and payload, forcing the Luftwaffe to use the Heinkel He 111 for other missions.

Apparently excited by the possibilities of an aircraft with the payload and range of the He 177 combined with higher performance than the Ju 88, the RLM promulgated the specifications for "Bomber B" in July 1939.

The specification called for a new medium bomber with a maximum speed of 600 km/h (375 mph), able to carry a bomb load of 4000 kg (8,820 lb) to any part of Britain from bases in France or Norway.

The Vulture had four six-cylinder cylinder blocks connected to a common crankcase and crankshaft, to make a larger displacement X-block design.

The Avro Lancaster and Handley Page Halifax designs formed the backbone of RAF Bomber Command for the remainder of the war.

[2] Simultaneously with the early development of the "coupled" engines, Daimler-Benz's began work on a 1,500 kW class design using a single crankcase.

This state of affairs at BMW led to the company's engineering staff being redirected to place all efforts on improving the 801 to develop it to its full potential.

With the Focke-Wulf and Dornier projects as first and second backups, the Technisches-Amt technical development office of the RLM started using these other designs as experimental testbeds.

This dramatically increased the complexity of wiring the planes and the chance that one of the many motors would fail was considerable but that was not considered terribly important—it was felt that the Junkers design would work anyway.

For comparative purposes, the nearly-equal displacement Wright Twin Cyclone radial engine was powering the American B-25 Mitchell twin-engined medium bomber with some 1,270 kW (1,700 hp) apiece of output, even with the B-25 having only a top airspeed of some 440 km/h (273 mph) at a take off weight of 15.9 tonnes (35,000 lb).

Prototypes of both designs with these engines were ordered, although the Fw 191 was just getting into the air with the BMW 801 radials at this point and the Ju 288 was showing a continual tendency to break its main landing gear on touchdown, partly due to its undercarriage problems caused by its complex method of stowing the oleo struts during retraction.

In June 1943, the T-Amt finally gave up; by this point, even if the Jumo 222 started working reliably, as it had begun to do in the summer of 1943, a shortage of the metals needed for the high-temperature alloys it used meant it would not be able to enter production anyway, with just under 300 development powerplants built.