Немецкий тяжелый бомбардировщик Heinkel He 177 "Гриф" времён Второй мировой войны.

German heavy bomber during WW2

The Heinkel He 177 Greif (Griffin) was a long range heavy bomber flown by the Luftwaffe during World War II. The introduction of the He 177 to combat operations was significantly delayed, by both problems with the development of its engines and frequent changes to its intended role. Nevertheless, it was the only long range, heavy bomber to become operational with the Luftwaffe during the war. The He 177 had a payload/range capability similar to that of four engined heavy bombers used by the Allies in the European theatre. Work on the design began in response to a 1936 requirement known as Bomber A, issued by the RLM for a purely strategic bomber. Thus the He 177 was intended originally to be capable of a sustained bombing campaign against Soviet manufacturing capacity, deep inside Russia. In contrast to its heavy payload and very wide, planform, the specifications called for the design to have only two very powerful engines. To deliver the power required, the He 177 needed engines of at least Engines of this type were new and unproven at the time. The Daimler Benz DB 606 power system that was selected, in conjunction with its relatively cramped nacelles, caused cooling and maintenance problems, such that the powerplants became infamous for catching fire in flight, and contributing to the He 177 gaining nicknames from Luftwaffe aircrew such as Reichsfeuerzeug ("Reich's lighter") or Luftwaffenfeuerzeug ("Air Force lighter"). The type matured into a usable design too late in the war to play an important role. It was built and used in some numbers, especially on the Eastern Front, where its range was particularly useful. It is notable for its use in mass raids on Velikiye Luki in 1944, one of the late war heavy bombing efforts by the Luftwaffe. It saw considerably less use on the Western Front, although it played a role during Operation Steinbock (the "Baby Blitz"), against the UK in 1944.

For aerodynamic cleanliness, Günter intended to dispense with the usual system of drag producing engine radiators and planned on using a surface evaporative cooling system instead. Such surface cooling, in the form of simpler surface radiators, had been used on British high speed racing seaplanes as early as 1929. This sort of system was pioneered on the eight examples built of the Heinkel He 119 high speed reconnaissance aircraft prototype series, already flying with the twin crankcase DB 606 "power system" engine with success from the beginning, and was also intended for use on the He 100 high speed fighter prototypes. The coolant water is pressurized, raising its boiling point, in this case to about 110 °C (230 °F). As the superheated water leaves the engine it enters an expansion area where the pressure drops and the water flashes to steam. The steam is then cooled by running it in pipes along the outer skin of the fuselage and wings. Before the design of the He 177 was finalized, it was clear that such a system would be incapable of dealing with the vast amount of heat generated by each of the twinned DB 601 based powerplants, forcing the abandonment of the idea of using evaporative cooling systems, in favour of conventional annular radiators fitted directly behind each propeller. These resembled, but were larger in capacity, than those fitted to the Junkers Ju 88 A bomber, and added to the He 177's weight and drag.

Günter's original intention had been to equip the He 177 with three cockpit controlled remote gun turrets, with two of them to come from the Junkers Ju 288 program, leaving one manned emplacement in the tail. Compared with the manned position, a remotely controlled, turreted defensive armament emplacement system traded technical complexity for reduction of size, weight and drag; it had the advantage that the gunner could be placed in a protected position, with the best possible view and with less risk of being blinded by the flash from his own guns. Although work on remotely controlled aircraft defensive systems had reached a relatively advanced stage in Germany in the late 1930s, progress in this field within Germany's aviation and armaments systems engineers and manufacturers was to prove insufficient to keep pace with the He 177. As a result, the He 177 had to be modified to accommodate larger and heavier manned positions, such as the manned rear dorsal turret usually fitted to almost all examples of the Greif, armed with a 13 mm MG 131 machine gun. That installation meant that the fuselage had to receive structural strengthening in several locations. Most of the later production aircraft did receive a remote forward dorsal turret, the Fernbedienbare Drehlafette (translated as "Remotely operated rotating gun mount" and abbreviated "FDL") 131Z, armed with two MG 131 machine guns, located at a point on the fuselage directly above the wing root's leading edge, with its rotating hemispherical sighting station dome located a short distance forward of the turret and slightly offset to starboard, just behind the forward cabin area. A compact tail gun position was fitted for rearward defense, armed with one MG 131 machine gun but its streamlined glazing meant that the gunner lay prone, severely restricting his comfort on long missions. A revised tail gun position with a bulged upper glazing was fitted to the He 177A 3 and later models, which permitted the gunner to sit upright. The revised design required a reduction of the lower end of the rudder surface for clearance. The MG 131 gun would often be replaced with a 20 mm MG 151 cannon or in a few instances, a semi experimental twin MG 131Z mount, with the twinned 13 mm calibre guns mounted one above the other, at the rear of the standard bulged upper glazing emplacement. Usually, a 7.92 mm MG 81 machine gun in a flexible mount was positioned in the upper starboard side of the cockpit nose glazing for defense against frontal attacks. The undernose, inverted casemate Bola gondola (a common ventral armament fitment on many German bombers), which was the full width of the fuselage where it emerged from under the nose and centered under the forward cabin, usually had a flexibly mounted, drum fed 20 mm MG FF cannon at the front end as added forward defense and a flexibly mounted MG 81 machine gun in the rear, for the initial He 177A 1. An MG 151 cannon replaced the forward MG FF cannon in later production models, with an MG 131 usually replacing the MG 81, for rearwards ventral defense.

The He 177 had Fowler type extensible trailing edge flaps, which covered the trailing edge of the wing, including those portions covered by ailerons. Each aileron comprised upper and lower portions, the latter arranged to slide rearwards with flap extension, while the upper part retained its function of providing lateral control for take off and landing. The original wing design did not fully take into account the stresses resulting from the operation of the Fowler flaps. A Rechlin report dated 9 October 1942 stated:
"The examination has shown that the strength of the He 177's wings is one third below that estimated by Heinkel. The reason for this is the uneven rigidity of the individual members with consequent deformation under load. This condition was not recognized by Heinkel at the proper time, the failure tests having been undertaken too late in view of the size of the structure." Tests on the 40th production A 1 aircraft in September 1942, revealed serious outer wing panel component damage after only some 20 flights, due to the aerodynamic stress from diving attack exercises. Costly and extensive strengthening was needed to solve the problem, which significantly increased the aircraft's weight. Starting with the later versions of the He 177A 3, the Fowler flaps along the outboard wing sections were no longer fitted and a strengthened wing design was introduced on the He 177A 5.

The inaccuracy of horizontal bombing during the Ural bomber program demonstrated weaknesses in German bombsights and created doubts about the effectiveness of level bombing of factories. While Wever had been advocating the Ural Bomber concept, others in the Luftwaffe were growing increasingly interested in dive bombing. and Hermann Göring's rescinding of the dive attack requirement on 15 September 1942, the barred gate type dive brakes on the wing's lower surfaces, placed just forward of each of the outboard ends of the Fowler flap panels, were omitted from all He 177A built after the initial A 0 pre production batch. A photo of one of the 12 "destroyer" He 177A 1/U2, heavy cannon armed test airframes, showed the retracted dive brake panel still fitted on the undersurface of the outer starboard wing.

During development, the anticipated weight of the He 177 increased so much that a main undercarriage design sufficient to handle the loaded weight, was difficult to achieve. The engine nacelles and wings had little room for the main undercarriage members, which needed to be longer than usual, for ground clearance for the large diameter four blade counter rotating propellers. After several extremely complex arrangements had been considered during initial design, a novel system was adopted. Instead of a wheel leg under each engine nacelle, two wheel legs were attached to the main spar at each nacelle, the outboard legs retracting upward and outward into shallow wing wells and the inboard legs swinging upward and inward into similar wells in the wing roots, with all units enclosed by flush fitting wheel and strut doors, which almost met under each engine nacelle when fully extended. During the retraction cycle, the forward oriented lever action lower gear strut sections, on which the wheels were mounted onto their axles, pivoted during the retraction cycle to a 90° angle from 120° when fully extended to the main gear leg, to be able to fit into the wheel wells. A conventional rearwards retracting single leg twin wheel arrangement for each main gear, with a design heavily influenced by the He 219's similar design main gear components, was used on the two prototypes built (one during the war, one post war) of the He 274 in France. Drawings were made for a tricycle gear arrangement for the four BMW 801E radial engine powered Amerikabomber entry version of the proposed He 277 by February 1943, which was also depicted with single main gear struts with twin wheels. For the He 177A's own landing gear maintenance needs, some two hours were required just to change a main gear tire, using special Heinkel designed capacity main gear jacks and blocks.

On 9 November 1939, the first prototype, the He 177 V1, was flown for the first time with Dipl. Ing. Leutnant Carl Francke, then chief of the Rechlin central flight test center, at the controls. The flight terminated abruptly after only 12 minutes due to overheating engines. Francke was pleased with the general handling and landing characteristics of the prototype but complained of some vibration in the airscrew shafts, the inadequacy of the tail surfaces under certain conditions, and some flutter which accompanied any vigorous movement of the elevators. The He 177 V2 made its first flight soon afterwards. Following Francke's initial flight, the He 177 V1 received several modifications suggested by the initial trials, including a 20% increase in the tail surface area. These changes were not applied to the He 177 V2 when another test pilot undertook the first diving trials, during which the V2 developed severe control flutter and broke up in the air. Following this incident, the tail surfaces of the V3, V4, and V5 prototypes were modified in a similar fashion to those of the He 177 V1. The He 177 V3 was allocated the task of power plant development. The V1 through V3 prototype airframes were all equipped with two counterclockwise rotating DB 606 A powerplants, while the V4 prototype, and all later aircraft throughout the production run of the A series, used a DB 606 A or DB 610 A engine on the starboard wing, and one clockwise rotating B version of the same powerplant on the port wing, so that the propellers rotated "away" from each other at the tops of the propeller arcs. The He 177 V4 was retained at Heinkel's test field at Rostock Schmarl (then known as Rostock Marienehe) where it undertook diving trials. While flying over the Baltic, the He 177 V4 failed to recover from a moderate dive, crashing into the sea near Ribnitz. It was discovered that the accident had resulted from the malfunctioning of an airscrew pitch control mechanism. On 17 November 1938, before the construction of the He 177 V3 and V4 prototype airframes had even been started, Ernst Heinkel had personally asked the RLM to set aside the V3 and V4 airframes for a trial installation of four separate Junkers Jumo 211 powerplants to overcome the concerns that the RLM Technisches Amt technical department's director Ernst Udet and Heinkel had expressed about the RLM's dive bombing priority for the He 177A, but was turned down for the trial fitment. The He 177 V5 incorporated a number of changes which were principally concerned with defensive armament installations. Early in 1941, during a simulated low level attack, both DB 606 engines burst into flames, and the V5 hit the ground and exploded. The He 177 V6 was the first aircraft equipped with main production type DB 606 A/B engines instead of the pre production units, which offered a slight increase in take off power by 100 PS to 2700 PS (2,663 hp, 1,986 kW). The He 177 V7 featured a revised nose section which, while generally following the contours of the nose sections employed by the previous prototypes, was considerably reinforced and embodied fewer glazed panels. In September 1941, the He 177 V8, the last of the prototypes which had a different, "bullet like" cockpit shaping and construction from the production He 177A series aircraft, was made available for engine tests. However, owing to the urgency of other development work it was returned to Heinkel after only 40 days, and it was not possible to resume engine tests in the air until February 1942. The He 177 V1 to V8 and the A 0 pre production models are notable for having a broad bladed set of four bladed propellers, with blade shapes and profiles similar to those used on the Junkers Ju 88. These were not used on the production He 177A series aircraft. Photographs of the first eight prototypes show a largely circular fuselage cross section, especially forward of the wing root, with the A 0 series possessing flatter sides, dorsal and ventral surfaces of the main A series production aircraft. The choice of what was called the "Cabin 3" cockpit design on 20 September 1939 for the production A series run, placed a well framed hemispherical "fishbowl" nose onto the He 177A 0, giving it the generic "stepless cockpit", without the separate windshield for the pilot and co pilot, that beginning with Heinkel's own He 111 P almost all German bomber aircraft had in World War II, and indeed had on all eight of the prototypes with the earlier "bullet" nose design. The forward glazing of the He 177A's "stepless" cockpit had each set of its characteristic framing members, of four supporting frame members per set running in each orthogonal direction, running as the parallels and meridians on a globe would. Two sets of four almost square windows, themselves arranged in a square of four windows each on each side of the upper cockpit, just behind the "fishbowl's" rear edge, provided sideways vision from the cockpit for the pilot and crew. Photographic evidence shows these side windows were produced with slight differences in external appearance between those built by Heinkel (with its primary headquarters, Heinkel Nord plant near Rostock, and the satellite Heinkel Süd plants around Vienna) and those built by Arado Flugzeugwerke (nearby to the Heinkel Nord plant, with Arado based in Warnemünde), the only major subcontractor for the He 177A's airframes. Often, the two lower rows of the "fishbowls" windows in the nose glazing were made opaque, with the exception of the bombardier's protruding bombsight window offset to starboard in the lower nose glazing, either by painting them over or replacing them with metal panels that performed the same function.

The tendency of the twin crankcase, apiece DB 606 "power system" engines to catch fire became increasingly serious as the test programme progressed, and many of the He 177A 0 series of pre production prototypes were destroyed in accidents or engine related incidents. The DB 606 engine had first been introduced on the Heinkel He 119 and later used on other aircraft such as the Messerschmitt Me 261 where they functioned as intended, but the extremely tight cowlings on the He 177A led to considerable problems, the most common being in flight engine fires and engine overheating. There were several reasons for the flammability of the DB 606 engine as installed in the Greif engine nacelles. One was the common "central" exhaust manifold, serving a total of 12 cylinders, on the two inner cylinder banks of the twinned DB 601 component engines making up a DB 606. This central exhaust system routinely became excessively hot, causing the usual accumulation of oil and grease in the bottom of the engine cowling to catch fire. When the pilot throttled back there was a tendency for the mechanical fuel injection pump on each component DB 601 engine to "lag" in its response, delivering more fuel than was required by the engine. In addition, the fuel injection pump connections often leaked. To reduce the aircraft's weight, no firewall had been provided, and the aft end of each DB 606 was fitted so close to the main spar — with the rear two thirds of the component powerplants' engine blocks being placed behind the wing's leading edge — that there was insufficient space for the fuel/oil fluid lines and electrical harnesses. The engines' exterior surfaces within the cowlings were frequently saturated with fuel and oil from leaking connections. At high altitude the oil tended to foam due to a badly designed oil pump,</blockquote>

Starting with the He 177A 3/R2, the engines and nacelles were redesigned to eliminate the tendency for engine fires. The new "power system" was the Daimler Benz DB 610, which consisted of two Daimler Benz DB 605s coupled into a single unit like the DB 606. With the introduction of the DB 610 came several improvements, including the relocation of the engine oil tank, a changed oil flow pipe, an improved oil cooler, through the Erprobungsstellen personnel and establishments, were responsible for backing the substantial numbers of upgrades to the He 177A from the time of the cancellation of its dive bombing requirement in September 1942.

In addition to carrying a variety of bombs, torpedoes, and guided weapons, the He 177 was tested with a number of unorthodox offensive armaments. The first of the experimental weapons fitments known to have been tested was the 12 examples of the He 177A 1/U2 Zerstörer variant, which was armed with a pair of limited traverse 30 mm MK 101 cannons in the extreme front of a dramatically enlarged Bola ventral gondola (beyond the hemispherical "fishbowl" nose glazing), and intended for ground attack, train busting, and possibly long range anti ship raids. These aircraft were also intended to be used against Allied long range reconnaissance and bomber aircraft operating over the Atlantic Ocean, which were posing a danger to the Kriegsmarine's U boat fleet. Later, when assigned to flak suppression sorties in the area of Stalingrad during the winter of 1942, Luftwaffe forward maintenance units modified a small number of He 177A 3s, fitting a 50 mm Bordkanone BK 5 cannon with a 21 round magazine within the aircraft's undernose Bola gondola, with the long barrel protruding well forward, beyond the glazed "fishbowl" nose. This variant was unofficially dubbed the Stalingradtyp. Although a small number of He 177A 3/R5 models were to be built from scratch, with the larger PaK 40 based, autoloading 75 mm Bordkanone BK 7,5 autocannon in the Bola location fitted with its 12 round magazine, structural problems caused by the 75 mm weapon's recoil meant that the Stalingradtyp did not see combat use outside of the original, BK 5 armed handful. Five He 177A 5s were experimentally equipped in January 1944 with batteries of 33 obliquely mounted 21 cm (8¼ in) calibre rocket mortar tubes, physically similar to the BR 21 single units already in use with single and twin engined Luftwaffe fighters for bomber destroyer missions, and also likely to have been similarly derived from components of the Nebelwerfer infantry barrage rocket system. The nearly three dozen launch tubes placed in a Greif's fuselage in such a manner were meant to create the Grosszerstörer ("Big Destroyer") flying battleship, designed to break up and destroy the tight combat box defensive formations used by USAAF daylight bombers over Germany. The bomb bays and fuselage housed auxiliary fuel tanks were removed on these aircraft in order to provide space for the spin stabilized 21 cm (8¼ in) rockets and their launch tubes. The tubes were inclined to fire upward at an angle of 60° to the horizontal, and slightly to starboard. The tubes could be fired individually, simultaneously, or in two salvoes of 15 and 18. Tests with fixed balloon targets showed the potential of this system, and limited operational trials against US Eighth Air Force bomber streams were authorized. The aircraft were operated by Erprobungskommando 25, flying out of the Baltic coastal Erprobungstelle facility at Tarnewitz. The intended mode of operation required the Grosszerstörer He 177s to follow the enemy bomber formations, passing below (as with a Schräge Musik cannon fitment) and to port of the target, maintaining a difference of altitude of 2,000 m (6,560 ft) beneath the targets at the time of the attack. A few trial daylight operations were flown but no contact was made with Allied bomber formations, and as the escort fighters were becoming ever more numerous in the manner of air superiority purpose "fighter sweeps" well ahead of the massed USAAF bomber formations, starting in early 1944 as ordered by then Maj. Gen Jimmy Doolittle the entire scheme was abandoned.

Experimental defensive weapon fitments were also fitted to a small number of He 177As set aside for such trials, mostly at the Erprobungstellen test detachment fields. One He 177A 1, s/n 15155 and bearing the Stammkennzeichen GI+BP, was fitted with the first ever example of a remote controlled twin gun "chin turret" at the front of its Bola undernose gondola. The type of guns fitted was not recorded, but the date on which GI+BP was written off following a mishap in May 1943 would place the fitting of its experimental "chin turret" simultaneously with the lead up to the May 1943 service introduction of the "gunship" USAAF Flying Fortress, the YB 40 (first flight September 1942), which pioneered the same type of forward defensive armament on the best known American heavy bomber to attack Germany. Similarly, the much anticipated Hecklafette HL 131V "quadmount" manned tail turret, fitted with a quartet of 13mm MG 131 machine guns, was tried in the late spring and summer of 1943 on a trio of A 3 examples set aside as the V32 through V34 prototypes, but that innovation never made it to production status, never existing as more than a series of engineering department mockups with Heinkel and Junkers, among others (for their aircraft designs that were intended to mount them) and working prototypes. The HL 131V turret's design originated with the Borsig division of Rheinmetall Borsig (the manufacturer of the guns themselves) and was a design with promise, using hydraulic drive to both elevate the turret's side mount gunmount elevation units through a +/ 60º vertical arc either side of level, with a capability for horizontal traverse (of the entire turret) of some 100º to either side, all at a maximum traverse angular speed of 60º per second. One development proposed during 1943 was to create a chin turret using the earlier Hecklafette's quadmount gun elevation assemblies to either side of a new, remote control traverse core as the Bugstandlafette BL 131V, located at the forward end of the He 177A's Bola undernose gondola. However, engineering studies of the quadmount chin turret project revealed that its fitment, proposed for a number of the later He 177A variants and the He 177 V104 prototype airframe, would lower airspeed by about 30 km/h (19 mph) and reduce the deployable bombload by a full tonne, making the BL 131V concept unacceptable, and prompting the idea of using a chin turret mount version of the FDL 151Z twin cannon remote turret instead for the B series, four DB 603 engined He 177Bs, close to what had been pioneered with the GI+BP airframe early in 1943. Even with its unsuitability for the He 177A, the BL 131V quadmount nose turret was prototyped for armament tests at the Erprobungsstelle Tarnewitz for potential fitment and use on the He 177B V104 prototype airframe; and had, by mid July 1944, completed its tests.

Flight testing of the He 177 in late summer 1942 revealed deficient stability around the yaw and pitch axes, resulting in extremely poor bombing accuracy when using the Lotfe 7 bombsight. The main reason for this was the drifting motion of the aircraft in flight due to its relatively short, round fuselage. Shortly after these tests, the third production A 1 example (factory serial number 15153, with Stammkennzeichen of GI + BN) had its fuselage lengthened by 160 cm (63 in) just aft of the trailing edge of the wing. The modified aircraft, with the longer distance of the "tail moment", showed a marked degree of improvement in yaw and pitch axis stability, enough to mandate the construction of the He 177A 3 and all subsequent models of the He 177A with the lengthened fuselage. He wrote that the in flight handling characteristics of the He 177A 5 were " positive about all axes, but the controls were all remarkably light for such a large aircraft. Indeed I had the feeling that the elevator was dangerously light and I was all too aware of the intelligence reports of He 177s breaking up in the air so I decided to treat this control very gently The aircraft had an automatic pull out device and an acceleration warning apparatus fitted, but it really was nailbiting to have to treat a giant like this immense Heinkel bomber as if it were made of glass. The stalling characteristics with flaps and undercarriage lowered, the aircraft buffeted violently at 140 km/h (87 mph) before the nose dropped at 135 km/h (84 mph). The buffet experienced was so violent that I had some concerns over structural damage. Somehow the He 177 always conveyed an impression of fragility despite its size." He added that it was "one of the very few German aircraft of the period that I tested that I did not enjoy flying".

Due to the continuing problems with the DB 606's configuration and engine accommodation design, much development work was done in order to rectify engine complications. This included a complete redesign of the original He 177, primarily through newer wing designs and layouts to improve the engine installation design, in conjunction with the A 3 subtype's lengthened rear fuselage, intended to create a four engined version of the Greifs airframe. The first concerns over the coupled engine vs. four separate engine issue for the He 177 emerged in mid November 1938, as Ernst Heinkel had requested that two of the under construction airframes for the eight He 177 prototypes to be fitted out with four individual engines in place of the coupled engine arrangements, eventually specifying that the V3 and V4 airframes get four individual Junkers Jumo 211 engines in an in plant corporate meeting on 17 November of three He 177B prototypes, designated He 177 V101 to V103. He stated on 10 August: "The He 177A 4 and A 5 will be produced as before. The He 177B 5 will be tackled with vigor. It will be built in series as soon as possible." was converted from a mid production He 177A 3 airframe (number 535 550, with Stammkennzeichen of NN + QQ), the V102 being converted from the eighth He 177A 0 production prototype aircraft (which required the He 177A 3 specification aft fuselage lengthening), and the V103 being converted from an existing, early production He 177A 5 airframe, with all three airframes initially retaining the production 177A style single vertical tail surfaces. Although no photographs are known to exist verifying their fitment, the general arrangement Typenblatt drawing for the V101 airframe — bearing the "B 5" subtype designation within the drawing's title block — showed that it was intended to be uniquely fitted with a small area matching vertical pair of so called pivoting "drag rudders" mounted, one per side, a short distance in from the horizontal stabilizers' tips, directly inline with the inner engine nacelles, to simulate "engine out" conditions. Each of the pivoted "drag rudders" were to have their area divided equally above and below the plane of the stabilizer. Because flight testing had revealed that the single tailed V101 exhibited an increasingly serious stability problem with higher airspeeds, the subsequent prototype, the V102, was both the first He 177B example to fly, on 20 December 1943, with the quartet of DB 603 engines, in combination with a brand new empennage of twin tail configuration, fitted to it during the early autumn of 1943. When the V102 was tested later that autumn while still flying with its A series wing and powerplants before its own pair of B series "four engine" wing units were ready, the new twin vertical tails gave the V102 significantly better in flight handling compared to the original 177A style empennage of the V101, except during the landing approach when the Fowler flaps were extended during its own initial flights with the twin tails in November 1943. On 24 February 1944, as the USAAF's Big Week strategic bombing campaign against Germany continued, particularly against targets in northern France involving V weapons installations — a meeting was held at the all turf surfaced Wiener Neustadt military airfield. Erhard Milch, and fellow guests Oberst Edgar Petersen and Oberstleutnant Siegfried Knemeyer (Göring's top aviation technology expert), each had a chance to fly the now four engined V102 prototype after the B series set of wings had been fitted. Knemeyer stated that he could not believe a four engined heavy bomber could possess the "excellent handling qualities" that the V102 displayed. The only verifiable wartime photograph of any of these He 177B prototypes in an intact condition is one of the V101, parked outdoors on a foggy German airfield, most likely the Heinkel Sud factory airfield at Schwechat. One additional surviving photo, showing what looks like a He 177B series prototype from the right side with a production style A series single vertical tail surface set, and bearing the Stammkennzeichen code of NE+OD, does not match any item of the surviving documentation for the four known 177B series prototypes ordered, built or flown before the end of the war, and possessing one of the upgraded, upright seating A 5 subtype's tail gunner's emplacements, as well as the usual twin dorsal turret defensive armament of the He 177A 5 subtype. The He 177B was also intended to introduce a slightly enlarged, somewhat more aerodynamic fully glazed nose. It somewhat echoed the lines of the nose glazing from the Airspeed Horsa British troop glider in a side view comparison,, carrying a quartet of MG 131 machine guns, was intended for installation on the prototypes. The Hecklafette HL 131V four gun manned tail turret system would have been standardized on the production B series aircraft, but never went beyond the mockup and working prototype stage, with a trio of the prototype tail turret units documented as being fitted to the He 177 V32 through V34 A series DB 610 powered prototype airframes for trials. The cumbersome four strut main landing gear of the A series was retained for the B series prototypes, even though the height, meant to allow clearance for the A series' pair of large four blade propellers, was not changed – the outer edge of the DB 603's inner engine nacelle/wing surface juncture was located right at the "centreline" of each of the twin pairs of A series main gear strut locations, on all four of the B series prototypes. The first flights of the He 177B prototypes, starting with the He 177 V102 on 20 December 1943, occurred between late December 1943 and early January 1944 in the vicinity of the Vienna Schwechat airfield, at the firm's Heinkel Süd production facility. An additional prototype, the V104, whose purpose was to be the "finalized" pre production prototype for the He 177B 5, and also meant to be a twin tailed prototype like the earlier V102, was being completed thereby order from the RLM, converted from an early production He 177A 5. through July 1944, repeated Fifteenth Air Force bombing raids on German aircraft production facilities in Vienna, and on 8 July destroyed the airworthy V103 and the incomplete V104 at the Zwölfaxing factory airfield of the Heinkel Süd complex, setting back plans to produce any series examples of the B 5 version. Arado Flugzeugwerke, which had been the major subcontractor for the A series Greif airframes, was fully involved at that time with the production of its own, much more advanced Arado Ar 234 B turbojet powered reconnaissance bomber, and was not able to handle the anticipated demand from Heinkel to produce the B 5 by October 1944. Arado would not have been able to start the He 177 B 5's production for another month (November 1944) due to its own focus on the Ar 234 B. The adoption of the Emergency Fighter Program in early July 1944 dealt the final blow to the entire He 177B development program, with the Heinkel He 162 Spatz jet fighter being the only new Heinkel aircraft design allowed into production.

Beset by technical difficulties in development, the He 177 had a troubled history in service. Unduly demanding design requirements of long range, high speed, heavy bomb load, and the formerly required dive bombing capability compounded the problems. Although the He 177 entered service in 1942, it was far from operational. In an assessment of the aircraft on 9 April 1942, the newly activated Erprobungsstaffel 177 reported that the Greif had good flying characteristics, but had unacceptable engine troubles and problems with its airframe strength. As an emergency measure, it was used to supply the encircled 6th Armee at Stalingrad, where it was found to be unsuited for the transport role, carrying little more cargo than the smaller and more reliable Heinkel He 111, and proving useless for the evacuation of wounded. As a result, the He 177s reverted to bombing and flak suppression missions near Stalingrad. Only thirteen missions were flown, and seven He 177s were lost to fire without any action attributable to the enemy. As the war progressed, He 177 operations became increasingly ineffective. Fuel and personnel shortages presented difficulties, and He 177s were sitting on airfields all over Europe awaiting new engines or engine related modifications. Of the 14 He 177A 3s (the primary subtype in use) that were sent out during Operation Steinbock, one suffered a burst tyre, and eight returned with overheating or burning engines. Of the four that reached London, one was lost to night fighters. These aircraft were brand new, delivered a week before the operation and not fully flown in, because the air unit had moved to a new airfield the day before and lacked sufficient maintenance personnel and material. Constant attacks against Luftwaffe long range combat units in France made continuous operations difficult. While Steinbock was unsuccessful, the He 177 did achieve some successes. During Steinbock crews typically carried two 1,800 kg (3,970 lb) and two 1,000 kg (2,200 lb) bombs. Climbing to 7,000 m (22,965 ft) while still over German territory, the He 177s approached the target in a shallow dive, both engines throttled back, the pilot putting his aircraft into a gliding descent to take it across the bomb release point at about 4,500 m (14,760 ft). After releasing the bombs the pilot re opened the throttles, but continued the descent at approximately 200 m (656 ft) per minute. The bombers typically re entered German airspace at an altitude of 750 m (2,460 ft), and headed back to base. By such means, the He 177s were able to keep up speeds of about during their withdrawal phase. The higher speed and constant change of altitude made interceptions difficult, increasing the survivability of the aircraft, but decreased bombing accuracy and concentration. With an average loss rate of 60% for bomber aircraft types used in Operation Steinbock, the He 177's loss rate below 10% made it the most survivable bomber in the campaign. On the Eastern Front, the most notable action by the He 177 was a mass raid of some 87 aircraft against railway targets in the Velikiye Luki area, about west of Moscow on 19 July 1944. The participating Staffeln flew in three large attack wedges of about thirty aircraft, each loaded with four 250 kg (551 lb) or two 500 kg (1,102 lb) bombs. During this action, carried out in daylight at altitudes in excess of 6,000 m (19,690 ft), losses were relatively light. The Soviet Air Force, equipped mainly for low level interception and ground attack roles, could do little to hinder the high flying bombers. In common with most piston engined German bombers, the He 177 was grounded from the summer of 1944 due to the implementation of the Emergency Fighter Program as well as the Allied bombing of German fuel production facilities.

All surviving He 177 A aircraft, including the photographed He 177 B wreck at Eger (Sudetenland) and both He 274 airframes completed in France post war, are known to have been reduced to scrap by the end of the 1950s, so there are no surviving examples.