Characteristics
Major differences between the He 274 and the He 177 A were abandonment of the twin coupled "power system" engine arrangement in favor of four independent DB 603A-2 engine units, an extended rear fuselage with a pressurized double glazed cockpit of nearly identical external appearance to the 177A's "Cabin 3" nose, longer wingspan, a twin tail fin empennage and a more conventional set of twin-wheel main undercarriage, abandoning the cumbersome four-strut main gear system of the He 177A.
The He 274 also featured a pressurized compartment for a crew of four, this employing double walls of heavy-gauge alloy, hollow sandwich-type glazing and inflatable rubber seals, a pressure equivalent to that at 2,500 m (8,200 ft) being maintained at high altitude. Largely unnecessary defensive armament was restricted to a single forward-firing 13 mm (.51 in) caliber MG 131 machine gun and remotely controlled dorsal and ventral Fernbedienbare Drehlafette FDL 131Z gun turrets each containing a pair of MG 131s and with the dorsal turret operated from a slightly offset plexiglass domed sighting station in the roof of the flight deck as most A-series He 177s were, with the ventral unit aimed from the rear of the ventral Bola gondola. The powerplants selected were the same Daimler-Benz DB 603A Kraftei "power-egg" unitized engine installations, complete with their He 219-style annular radiators that were placed on the wings of the quartet of ordered He 177B prototypes, but for the He 274's use, added DVL-designed TK 11 turbochargers, one per engine, for better power output at high altitude.
The significance of this design is that had this aircraft entered production and been used in operations over England it would have been impossible for Allied fighters to intercept over the target, owing to its extreme high altitude performance.
Read more about this topic: Heinkel He 274