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Heinkel He 277

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Heinkel He 277
Company typeAircraft project
IndustryAerospace
Founded1943
FounderErnst Heinkel
FateProject cancelled in 1944
Headquarters
Schwechat
,
Austria (then part of Germany)
ProductsHeavy bomber aircraft (project)


Template:Infobox aircraft

The Heinkel He 277 was conceived as a long-range, four-engine heavy bomber derived from the He 177, planned for deployment by the German Luftwaffe during World War II. Its primary distinction lay in its propulsion system. Unlike the He 177, which featured problematic paired engines arranged in twin nacelles, the He 277 was designed to incorporate four separate unitized BMW 801E fourteen-cylinder radial engines, each housed individually.

No completed prototype of the He 277 ever materialized.[1] The worsening state of Germany’s aviation industry in the latter stages of the conflict, combined with competition from alternative long-range bomber designs by other manufacturers, ultimately led to the project's termination.

Designation

For decades following the war, some historical aviation sources claimed that early in World War II, Reichsmarschall Hermann Göring grew so exasperated with the He 177A’s troublesome twin DB 606 "coupled" engines that he prohibited Ernst Heinkel from developing or even discussing a four-engine variant of the He 177 airframe—referred to as the "He 277"—around late autumn of 1941. According to these accounts, this ban was only lifted after Heinkel appealed directly to Adolf Hitler, who not only authorized naming the new version "He 277" but also overruled Göring’s restriction. During this period, Heinkel reportedly used the designation "He 177B" as a covert label to conceal the project from Göring and the RLM.[2][3]

File:Daimler Benz DB 610.jpg
The problematic DB 610 "welded-together engine" used in the He 177A-5 – similar to the DB 606A/B units, each weighing approximately 1.5 tonnes
File:Bundesarchiv Bild 183-B19957, Edgar Petersen.jpg
Oberst Edgar Petersen, commander of the Luftwaffe’s test station network ("KdE").

Contrary to these narratives, statements made by Göring in August 1942 responding to Oberst Edgar Petersen’s reports—Petersen being head of testing at Erprobungsstelle Rechlin—regarding solutions for the severe engine troubles of the original Heinkel He 177A powerplants appear inconsistent with earlier claims. These remarks suggest Göring believed the He 177A employed four distinct engines and disparagingly referred to its coupled DB 606 and DB 610 powerplants as monstrous zusammengeschweißte Motoren ("welded-together engines").[4] Furthermore, he expressed eagerness for a true four-engine bomber version to be developed and produced. Notably, Ernst Heinkel initiated efforts toward a genuine four-engine configuration for the original He 177 as early as November 17, 1938—prior to building prototype airframes V3 and V4—by requesting that these frames be reserved for testing four separate unitized Junkers Jumo 211[5][6] engines to address concerns raised by RLM technical director Ernst Udet and Heinkel himself regarding the mandated dive-bombing role for the He 177A. This request was declined. Nevertheless, certain sources distinguish between the He 177B and He 277 as separate projects.[7]

The misconception that "He 177B" served as a cover name for "He 277" may stem from RLM records dated February 1943—which postdate Göring’s complaints by six months and follow Heinkel’s conceptualization of the paper-only "He 177H" high-altitude precursor to the later He 274 by eighteen months—that listed approved development projects under the Heinkel firm. These included only variants A-5 (heavy bomber), A-6 (high-altitude bomber), A-7 (long-range version), and explicitly the He 277 itself. This date marks when RLM officially assigned project number 8-277 to this design.[8] By late spring of that year, RLM anticipated production of three prototype V-series aircraft plus ten pre-production service test models designated He 277A-0 at Heinkel's Schwechat facility in Austria starting in 1944.[9]

The fuselage concept for the He 277 originally derived from plans for the final "coupled-engine" variant of the He 177—the long-range A-7 model—which was itself intended as a foundation for a four-engine version known initially as the He 177A-10 (later redesignated as He177B-7 during late summer of1943).[10] The significant modifications seen in the overall design philosophy of the He277 occurred following emergence of the Amerikabomber requirement in1941; notably reflected in changes to general arrangement drawings during this period and influenced by earlier work on the six-engine P.1064 strategic bomber project from1942. Initially based on adapting the fuselage of the He177A-7, by spring1943 design efforts shifted toward creating an entirely new and broader fuselage resembling that of the He219, better suited for accommodating a tricycle landing gear configuration favored by some German designers.

The principal reason behind adopting low-drag "coupled" engines for the original He177A—a dive bombing capability mandated by RLM but strongly opposed by Ernst Heinkel since late1930s—was rescinded by Göring five months prior to RLM approval of the "He277" project in February1943.[11] Subsequently, work on a straightforward four-engine derivative designated as He177B commenced at least by late summer1943. Official documentation from August1943 shows a factory general arrangement drawing labeled with RLM number 8-177 and marked B-5 for what became known as prototype V101—a fully sanctioned evolution within the original ‘’Greif’’ series unrelated directly to the advanced ‘’He277’’ project competing under Germany’s ‘’Amerikabomber’’ program.[12][13] The first flight featuring four individual engines on an original A-series airframe occurred with ‘’He177 V102’’, which flew on December20,1943; powered by four likely unitized Daimler-Benz DB603 engines cooled using annular radiators similar to those on ‘’He219’’.[14]

Overall, there were four distinct initiatives toward developing authentic four-engine versions of the A-series ‘’Greif’’ initiated by Ernst Heinkel beginning November1938: an unbuilt ‘’He179’’ with four Junkers Jumo211 engines; ‘’He177B’’, which produced four prototypes with three flown before war’s end; ‘’He274’’, with two prototypes started before war’s conclusion and later completed and flown postwar in France; and finally ‘’He277’’, which never advanced beyond partial airframe construction before cancellation in May1944.

Design characteristics

File:Duxford Blenheim.jpg
The restored Bristol Blenheim Mk.I’s nose design reflects the intended forward cockpit shape for the He 277 Amerikabomber, which also featured an upper cockpit glazing arrangement similar to that of the Avro Lancaster.

By mid-1943, Heinkel's engineering department had produced general arrangement Typenblatt drawings for the He 277[15] that revealed a sophisticated heavy bomber design. It featured a "shoulder-mounted" wing with an area of 133 square meters (1,431.6 sq. ft.) and a wingspan measuring 40 meters (131 ft 3 in). Propulsion was provided by four independent BMW 801E engines, each delivering 1,471 kW (2,000 PS, 1,973 hp) at takeoff, driving propellers up to four meters in diameter.

The aircraft's retractable landing gear was planned to be either a conventional tailwheel or a tricycle nosewheel setup. Each main gear unit included twin wheels and retracted into the inner engine nacelles—forward when paired with the nosewheel configuration and rearwards for the conventional gear layout. Heinkel had prior experience with retractable tricycle undercarriages, having implemented one in late 1939 on the Heinkel He 280 jet fighter prototype,[16] followed by its use on the Heinkel He 219 night fighter.

The primary crew compartment of the He 277 was designed as a heavily glazed "stepless" cockpit with a "greenhouse" framework—a characteristic common among many late-war German bomber designs. Positioned directly behind the extensively glazed nose section, this cockpit enclosure seamlessly merged with the nose glazing contours and extended above the forward dorsal fuselage line. A rearward extension ran along the top of the fuselage, integrating smoothly with the forward surface of the upper dorsal turret and continuing just ahead of the inner engine cowlings. The fuselage itself was deep and nearly slab-sided in cross-section, with side profile lines closely resembling those of the He 219.[17]

This resemblance extended to the defensive armament layout proposed for the He 277, which featured one forward and two rear-facing stepped positions along its slightly rounded dorsal and ventral fuselage surfaces—similar to those found on early prototypes of the smaller night fighter.[18] These were intended for manned aft dorsal and remotely operated aft ventral turrets. The aft ventral turret was relocated approximately two meters rearwards compared to early He 219 V-series prototypes to accommodate the rear section of the bomb bay.[19]

The twin tail empennage design of the He 219 night fighter likely inspired the similar tail assembly on the He 277, which offered enhanced aerodynamic stability compared to the single vertical fin used on the He 177A. This was confirmed from late December 1943 onward by flight tests of the four-engined He 177 V102 prototype featuring twin tails.[20] The twin vertical stabilizers also facilitated easier installation of a powered, traversable defensive tail turret.[21]

Heinkel’s Typenblatt drawings indicated provisions for four underwing hardpoints—two per wing panel located outboard of each engine nacelle—potentially enabling carriage of external ordnance or drop tanks to extend operational range or payload capacity.

A May 1943 document from Heinkel detailed possible offensive bombload arrangements and consumable weights (such as fuel) for different bomb bay configurations on the He 277. Two bomb bay sizes were evaluated: one measuring 1.5 x 7.5 meters designed for a tailwheel undercarriage version, and another sized at 1.75 x 7.0 meters intended for a tricycle landing gear variant within a fuselage width of approximately 1.90 meters. The lightest bomb load consisted of six SC 500 bombs (each weighing about 500 kg or 1,100 lb) regardless of configuration. The tricycle-geared model with its wider fuselage could carry a larger fuel load (around 12,200 kg or 26,895 lb), enabling an estimated maximum range near 11,100 km (6,900 mi)—matching that of the earlier Me 261. This underscored what might have been achievable if the He 277 had been fully developed from inception as part of Germany’s Amerikabomber competition.[22][23]

Armament

The defensive weaponry concept featured five turrets, with two operated by crew members and three controlled remotely. Positioned beneath the aircraft's nose in the "chin" location was a remotely controlled Fernbedienbare Drehlafette (FDL) 151Z turret equipped with twin 20 mm MG 151/20 cannons. Along the upper fuselage, there was a remotely operated FDL 151Z turret at the forward dorsal site and a manned Hydraulische Drehlafette (HDL) 151Z turret situated at the rear dorsal position; both turrets housed two MG 151/20 cannons each. Just behind the bomb bay on the underside of the rear fuselage, a remotely operated ventral turret carried an additional pair of MG 151/20 cannons. The gunner for this ventral position would lie prone, facing backward in an offset position to starboard, utilizing a slightly protruding blister-like ventral gondola for aiming. At the tail end, a manned Hecklafette (HL) 131V turret was installed, armed with four 13 mm MG 131 heavy machine guns. This four-gun Hecklafette turret was also intended for use on other Amerikabomber designs, including Heinkel's proposed evolutions of the He 177A airframe and a conceptual "C-version" of the He 219 night fighter.

The increasing requirement for a sophisticated gun turret—one not yet produced in quantity by Borsig, the manufacturer responsible—resulted in an alternative twin-cannon "HL 151Z" variant featuring a single MG 151/20 cannon mounted on each side of the turret. By March 1944, only a limited number of these twin-cannon tail turret prototypes had been constructed for ground testing purposes. One such experimental twin-cannon tail turret was installed on an He 177A airframe to facilitate trials.

Certain side-profile line drawings of alleged "He 277" aircraft—often found in aviation history sources that propagate the inaccurate "He 177B/He 277" narrative—depict what may be an early He 177A-7-based version of a later Amerikabomber contender. This illustration shows the He 177A's "Cabin 3" standard cockpit along with four Kraftei DB 603 inverted V12 engines, derived from the He 219 and actually utilized on the four He 177B prototypes (V101 through V104). These drawings also include the now-abandoned Bugstandlafette BL 131V quadmount remote turret as a "chin turret," replacing the FDL 151Z system according to Heinkel's factory Typenblatt schematics. However, the BL 131V had been discarded in 1943 due to excessive weight—which reduced bomb load capacity by approximately one tonne—and because it decreased top speed by roughly 30 km/h due to increased drag. Consequently, its presence on any He 277 design proposals is highly improbable.

Competing bomber designs

During the period when the He 277 was under development, Ernst Heinkel faced rivalry from several other heavy bomber concepts and promising four-engine aircraft projects intended for similar roles. These included the Focke-Wulf Fw 300 and Ta 400, the Junkers Ju 390, the Messerschmitt Me 264, as well as Heinkel’s own He 274, a four-engine high-altitude derivative of the He 177.

The initial competitor to the He 277, primarily evaluated to identify the "most producible" bomber suitable for licensed manufacture due to Germany's constrained aircraft production capabilities, and also to determine the optimal long-range bomber fulfilling the spring 1942 Amerikabomber program requirements, was the Messerschmitt Me 264. This aircraft was designed specifically as a long-range bomber featuring a tricycle landing gear from inception. By late December 1942, Me 264 prototypes were already undergoing flight tests powered by four Junkers Jumo 211 engines—the same engine type Heinkel had requested on November 17, 1938, for the He 177 V3 and V4 prototypes. This timeline places these flights a year after Nazi Germany declared war on the United States, five months following the commencement of Eighth Air Force bombing raids over Nazi-occupied France, and two months prior to any documented approval for the He 277 project itself. Later iterations of the Me 264 prototypes were equipped with four BMW 801 radial engines each, potentially challenging engine availability that the He 277 would have required if it had entered productionTemplate:Fix/category[citation needed].

Development of the Me 264 was halted in May 1943 due to the necessity of conserving scarce strategic materials and because forecasts indicated superior performance from both the Focke-Wulf Ta 400 and the He 277.[24]

With American forces entering the European conflict in mid-August 1942, the Luftwaffe urgently required a well-armed bomber capable of extended range missions—something unattainable with available engines rated around 1,120 kW (1,500 hp). Persistent challenges in producing reliable high-output powerplants exceeding this threshold—which ruled out using DB 606 engines from earlier He 177A models due to their operational issues since combat service began in 1942—meant that strategic bombers needed six engines under approximately 1,500 kW (2,000 PS) each to undertake missions from Europe to targets in the United States and return safely while carrying an effective payload and sufficient defensive armament.[25] On July 3, 1943, this perspective solidified within the Reichsluftfahrtministerium (RLM), as no production decisions had been made regarding the still-unfinished He 277 design. Moreover, ongoing setbacks with Dessau’s development of the high-output Junkers Jumo 222 engine further complicated its proposed integration into the He 277.[26] Meanwhile, Blohm & Voss’s aviation division had successfully employed six engines on prototypes of their large BV 222 Wiking flying boat since as early as 1940. Recognizing this requirement for six engines on such aircraft types was also reflected by Messerschmitt AG’s conceptual "Me 264B" project—a six-engine variant featuring an expanded wingspan of approximately 47.5 meters (155 ft 10 in), incorporating two additional BMW 801 radial engines beyond its original four powerplants and equipped with a Hecklafette four-gun tail turret similar to that planned for the He 277.[24] On July 23, 1943, Heinkel received an RLM technical department order to design new wings for the uncompleted He 277 capable of accommodating either four Jumo 222 engines or six BMW 801s. This wing design was intended to cover around a 170 square meter (1,830 sq ft) area with a span near 45 meters (147 ft 7 in), reflecting RLM’s preference for a six-engine configuration for an Amerikabomber.[27]

In March of that year, Focke-Wulf proposed a six-engine variant of their Fw 300 bomber initially designed with four BMW 801E radials. Later in October, they introduced their more advanced Ta 400 model featuring tricycle landing gear and powered by six BMW engines identical to those intended for the Heinkel design. Concurrently, Junkers developed their Ju 390—a six-engine evolution of their Ju 290 maritime patrol aircraft—also utilizing six BMW radials like those planned for the Heinkel bomber. Both the Ju 290 A-8 and Ju390 A-1 variants were equipped with two Hecklafette quad-gun tail turrets; one positioned at the tail and another newly designed nose-mounted turret.[28]

By October of that year, Ernst Heinkel had assessed his own He 277 against Messerschmitt’s and Junkers’ four-engine models as well as six-engine designs such as Blohm & Voss’s BV222, Junkers’ Ju390, and Focke-Wulf’s Ta400. His evaluation concluded:

Template:Blockquote

Among these contenders mentioned by Dr. Heinkel—except for thirteen BV222 flying boats actually produced—only three Me264 prototypes and two confirmed Ju390 aircraft were constructed; none participated in combat operations against Allied forces.

The He274’s role as a high-altitude bomber positioned it more as an internal competitor within Heinkel’s own engineering resources rather than a direct rival to the He277. By late 1941, production of the He274 had been transferred to France’s Societe Anonyme des Usines Farman ("SAUF") facility in Suresnes to free up company capacity for other projects such as the He277 and the advanced Heinkel He343 jet-powered medium bomber concept. While some components for prototype airframes of both designs were under construction, neither aircraft reached flight status before war’s end.

Conclusion of the project

In April 1944, while the quartet of He 177B prototypes (He 177 V101 through V103) were airborne or nearly finished (V104) at the Heinkel-Süd plant in Schwechat, the Reichsluftfahrtministerium (RLM) instructed Heinkel to halt all development on the He 277 program. Additionally, all parts were mandated to be destroyed. No fully assembled He 277 aircraft were ever produced by Heinkel. This directive came just three months before the commencement of the "Emergency Fighter Program" (Jägernotprogramm) on July 3, 1944, which reprioritized all German military aircraft manufacturing. Following this shift, only the Heinkel He 162 Spatz lightweight jet fighter received authorization to advance into production by the RLM.

Specifications (He 277 standard design)

Template:Aircraft specifications/switch

See also

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Notes

References

  1. ↑ Griehl & Dressel 1998, p. 203
  2. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  3. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  4. ↑ Griehl & Dressel 1998, pp. 52–53
  5. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  6. ↑ Griehl and Dressel 1998, p.14.
  7. ↑ Nowarra (1972)
  8. ↑ Griehl & Dressel1998,p.179
  9. ↑ Griehl & Dressel1998,p.104
  10. ↑ Griehl & Dressel1998,p.196
  11. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  12. ↑ Factory drawing for first ‘’He177B-5’’ prototype (V101)
  13. ↑ Griehl & Dressel1998,p.166
  14. ↑ Griehl & Dressel1998,p.163
  15. ↑ Heinkel engineering department's He 277 general arrangement 3-view drawing for the nosewheel version
  16. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  17. ↑ Heinkel factory's He 219A Typenblatt drawing
  18. ↑ Heinkel factory sideview of a He 219 V-series prototype, with fuselage's original rear-facing armament mount "steps" showing
  19. ↑ Archived "Heinkel 219 prototypes" page.Wwiivehicles.com. Retrieved: 27 March 2019.
  20. ↑ Lua error in Module:Citation/CS1/Configuration at line 2123: attempt to index field '?' (a nil value).
  21. ↑ Griehl & Dressel 1998, p. 195
  22. ↑ Griehl & Dressel 1998, p. 184
  23. ↑ 12 May 1943-date Heinkel Flugzeugwerke bomb loadout chart for He 277 design evaluation
  24. ↑ 24.0 24.1 Griehl & Dressel 1998, p. 187
  25. ↑ Griehl & Dressel 1998, p.188
  26. ↑ Griehl & Dressel, pp.196–197
  27. ↑ Griehl & Dressel, p.197
  28. ↑ Griehl & Dressel, pp.192–193

Bibliography

  • Green, William. Warplanes of the Third Reich. London: Macdonald and Jane's Publishers Ltd., 1970 (4th Impression 1979). ISBN 0-356-02382-6.
  • Griehl, Manfred and Dressel, Joachim. Heinkel He 177-277-274, Airlife Publishing, Shrewsbury, England 1998. ISBN 1-85310-364-0. (Primary reference for article)
  • Gunston, Bill & Wood, Tony. Hitler's Luftwaffe. London: Salamander Books Ltd., 1977. ISBN 0-86101-005-1.
  • Wagner, Ray and Nowarra, Heinz. German Combat Planes: A Comprehensive Survey and History of the Development of German Military Aircraft from 1914 to 1945. New York: Doubleday, 1971.

External links

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