Heinkel He 274 - He 177 Ancestry

He 177 Ancestry

On 17 November 1938, the owner of the Heinkel aviation firm, Ernst Heinkel, requested permission from the RLM that two of the requested eight prototype airframes for the nascent He 177 heavy bomber project, specifically the V3 and V4 airframes, be set aside for a trial installation of four separate Junkers Jumo 211 powerplants. Herr Heinkel had foreseen that an individually engined version of his bomber would someday be preferred, quite unlike the requested fitment of the coupled pairs of Daimler-Benz DB 601 inverted V12 engines, each known as a DB 606, which ended up being fitted to all of the eight He 177 V-series prototypes at the request of the RLM, and the Luftwaffe High Command, with the concerned government agencies citing the desire for a dive-bombing capability to be present even with a heavy-bomber-sized offensive warplane, something Ernst Heinkel vehemently disagreed with.

By April 1939, interest in developing a high-altitude version of the He 177 had arisen, and on April 27, 1939, the first proposal for such an aircraft was presented to Heinkel by his firm's engineering staff. The aircraft was intended to have a reduced crew manifest of three people, with a fully pressurized nose compartment for the pilot and bombardier/forward gunner, and separate pressurized tail gun emplacement. The result, in December 1940, was the specification for the He 177A-2 high altitude bomber design, with a four-person crew manifest (pilot, bombardier, forward gunner and tail gunner) in the two specified pressurized compartments, and powered by the regular A-series pair of DB 606 coupled engines. The defensive armament had been reduced to a trio of Ferngesteuert-Lafette FL 81Z remote gun turrets, each with a twin-barrel MG 81 armament installation each in an upper nose mount, forward dorsal and (as part of the Bola casemate-style gondola under the nose) forward ventral location each, and a single MG 131 machine gun in an He 177A-1-style, pressurized manned flexible tailgun emplacement. The A-2 version had even been considered for a pioneering in-flight refueling capability, possibly using Ju 290 maritime patrol aircraft as the tankers - with such capability, the range of the A-2 would have been extendable to some 9,500 km (5,900 mi) of total flight distance.

The Heinkel firm had been working on practical cockpit pressurization methods and hardware for both the A-2, and slightly later A-4 versions (identical to the A-2, except for the fitting of a pair of the later DB 610 coupled engine "power systems") from 1940 through the late summer of 1941, when the DB 610-powered A-4's pressurized cockpit in provisional form, almost identical in external appearance to the standard "Cabin 3" He 177A-series production cockpit, was ready for tests and development.

By October 1941, a more developed "He 177H" specification for a high-altitude Heinkel-designed heavy bomber had emerged from the proposed A-2 and A-4 coupled-engine designs, with the intent of carrying a 2,000 kg (4,410 lb) bombload over a maximum range of some 3,000 km (1,895 mi), and accepted by the RLM for the first time, an individual four-engine installation was being considered for any He 177-based bomber airframe, with a quartet of either BMW 801 or DB 603 engines among the choices of powerplants being specified, with the same sort of reduced-armament defensive weapon format as the A-2 and A-4 were intended to have.

A pair of the early He 177A-0 pre-production prototypes were redesignated the He 177 V10 and V11 for the purposes of high-altitude trials, and were to be the first to test the A-4 pattern pressurized cockpit design at altitude, but only the V11 was actively used for the needed research, and managed to achieve an altitude of 9,200 m (30,200 ft) with complete success on August 9, 1943, with further tests continuing through October of that year, before both the V10 and V11 were grounded in April 1944.

In February 1943, any further work on the coupled-engined A-2 and A-4 designs was halted by order of the RLM, as the four-engined He 177H high-altitude design had gained in importance from that time, evidenced by Reichsmarschall Hermann Göring's derisive "welded-together engines" complaints in August 1942, regarding the He 177 A-series unending engine problems from the choice of the DB 606 and 610 "power systems" for the A-series operational aircraft.