Heinkel He 177 Greif – Innovation Comes at a Price
In the period between the wars, the concept of strategic bombing gained supporters who believed that this would be a way of achieving a quick victory in any future war and Germany thought they could achieve this with the He 177.
British politician Stanley Baldwin summed this up in a speech to parliament in 1932 aptly titled “A Fear for the Future” in which he used a phrase that became a mantra for those who believed in this new approach to war:
“The bomber will always get through.”
The systematic bombing of enemy cities, industry, and infrastructure, it was said, would quickly force any nation to surrender. As a result, many countries began work on the development of long-range heavy bombers specifically designed for strategic bombing.
By the time that the Second World War began in 1939, the US Army Air Force already had the Boeing B-17 Flying Fortress in service, the RAF had begun flight testing of the Short Stirling and the Soviet Air Force was equipped with the Tupolev TB-3.
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In contrast, the German Luftwaffe began the war without a single operational four-engine heavy bomber. This is the story of Germany’s attempts to build a strategic bomber: the innovative but complex, unreliable, and quirky He 177 Greif.
Under the terms of the Treaty of Versailles, Germany was banned from having an air force following the end of World War One. However, within a few months of the Nazi takeover of power in 1933, work began on the clandestine creation of a German air force, the Luftwaffe.
Its head was a man who believed passionately in the doctrine of strategic bombing, Walter Wever. Wever was appointed head of the Reichsluftfahrtministerium (German Air Ministry) in September 1933 and became the Chief of Staff of the Luftwaffe when its existence was formally announced in February 1935.
Although he had no flying training and had never served as a pilot, Wever embraced the notion of strategic bombing and he was in no doubt which nation would present the greatest threat to Germany in any future war: the Soviet Union.
Wever pressed for the development of a bomber capable of delivering a payload of over 3,000 lbs and with a range of more than 1,200 miles. The thinking was simple: if Germany was to be able to undertake strategic bombing to disrupt Russian armament production, it need an aircraft capable of attacking targets deep within Russia, beyond the Ural Mountains. Thus was created the idea of what became known as the Ural Bomber.
Under pressure from Wever, Dornier produced the Do 19, first flown in October 1936, and Junkers produced the Ju 89, first flown in December of the same year. Both were four-engine heavy bombers but in truth, neither was particularly impressive.
By the time these prototypes flew, Walter Wever was dead, killed when the aircraft in which he was flying crashed after take-off in the city of Dresden on June 3rd, 1936.
Neither his successor, Albert Kesselring, nor the Reichskommissar of Aviation, Hermann Göring, shared Wever’s belief in the need for a long-range bomber and both heavy bomber projects were cancelled in favour of the development of medium and dive bombers, ideal for close support but unsuitable for strategic bombing.
However, the Ural Bomber concept wasn’t entirely abandoned and by coincidence, on the very day that he died, a new specification was issued under Wever’s name by the Reichsluftfahrtministerium (RLM – German Air Ministry) calling for proposals for a new strategic bomber.
Bomber A was required to have a range of 5,000km and a speed of 300mph, performance in advance of that of any other bomber of the period. Heinkel had already been working on a high-speed reconnaissance bomber, the He 119, that used a low-drag design to create an aircraft that was significantly faster than most contemporary fighters.
This aircraft was powered by a Daimler Benz DB 606 powerplant, essentially, two coupled Daimler Benz DB 601 engines mounted inside the fuselage and driving a single propellor. The He 119 never went beyond the construction of a single prototype, but this powerplant concept was used in Projekt 1041, Heinkel’s response to the RLM specification for Bomber A.
This design, created by Heinkel’s Chief Designer, Siegfried Günter, envisaged a bomber with a wingspan of over 31m (over 100 feet) powered by two pairs of DB 601 engines mounted in two nacelles and driving two large, counter-rotating, four-blade propellors.
A mock-up was completed in November 1937 and the project was given the formal RLM identification He 177. However, the same month, RLM issued a startling addition to the original specification: the massive new aircraft was also required to be a dive-bomber!
This new requirement emerged from the experience of the German Condor Legion in Spain, where the bombsights used on German-level bombers proved unreliable and the most accurate bombing was carried out by the Ju 87 Stuka.
Initially, the specification required the new bomber to have only shallow angle dive bombing capability, but this was later changed to demand a dive angle of 60% in an aircraft of comparable size to the American B-17 Flying Fortress!
Ernst Heinkel’s understandable initial response was that this simply wasn’t possible, but a redesign was carried out to strengthen the airframe for dive bombing which also considerably increased the aircraft’s weight.
The prototype He 177V1 flew for the first time in November 1939, but it quickly became apparent that this aircraft’s innovative but complex design was going to cause problems.
Almost every aspect of the design of the He 177 was predicated on the need to keep drag to a minimum to achieve the required performance.
Each pair of DB 601, 12-cylinder, in-line water-cooled engines were mounted at an angle of 30˚ to create a 24-cylinder, inverted V powerplant. This was squeezed into nacelles that were as narrow as possible to reduce drag, but this meant that maintenance access was poor and the proximity of the engines caused overheating that could lead to the ignition of oil and grease within the cowling.
Any resulting fire was made worse by a tendency for leaks in the fuel injection systems for each engine.
To reduce weight, no firewall was installed behind the engines which projected back into the wings and close to the main spar. That was a particular problem because it meant that any fire in the nacelle could quickly cause a rapid failure of the main spar – several He 177s that experienced engine fires broke up in the air before their crews could bail out.
Originally, this aircraft was designed to have a radical evaporative cooling system that eliminated the need for drag-inducing radiators, but this proved impractical. Instead, annular radiators were installed at the front of each engine nacelle (a similar arrangement was used on the Ju 88), but engine cooling was always marginal on the He 177.
Even the defensive armament of the He 177 was designed to minimise drag. Rather than having bulky, manned turrets, it was originally intended to have three remotely controlled positions operated from the cockpit.
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However, early production aircraft were provided with a manned tail position armed with a single 13 mm MG 131 machine gun where the gunner lay prone (on a later version this was revised with a new position where the gunner could sit upright and the tail weapon was changed to a 20 mm MG 151 cannon).
Most production versions were also armed with a single Fernbedienbare Drehlafette (remotely operated rotating gun-mount), a low turret on the fuselage top armed with two MG 131 machine guns and controlled from a small glazed sighting station between the turret and the cockpit.
The undercarriage on the He 177 was also unique. Originally, it had been intended to have just two undercarriage legs, one mounted at the rear of each engine nacelle.
However, the increasing weight caused by the redesign to turn this into a dive-bomber meant that two separate legs were required on each side, each carrying one massive wheel. Limited space meant that while the inner legs retracted conventionally to the rear and into the nacelle, the outer legs rotated and retracted outwards into the wing.
This complex arrangement was difficult to service – just changing a wheel on the He 177 could take up to 2 hours.
Although externally it looked relatively conventional, almost every aspect of the He 177 introduced technical innovation and complexity.
The Air Force Lighter
Early flight testing of this aircraft did not go well. When the first prototype He 177 flew in November 1939, the flight had to be aborted after 20 minutes when the engines began to overheat. The second prototype was used for dive-bombing trials.
It broke up in the air and crashed. After further strengthening of the fuselage, the fourth prototype was again used for dive bombing tests. It dived straight into the Baltic, killing the crew. The fifth prototype was the first to be destroyed by an in-flight engine fire. Many subsequent prototypes and production examples would suffer the same fate.
When the He 177 became operational in 1942, none of its fundamental problems had been solved. In December of that year, the He 177 was pressed into service to supply the beleaguered German 6th Army at Stalingrad.
Only thirteen missions were flown but seven He 177s were lost, all to engine fires rather than enemy action. Although its formal name was Greif (Griffon), amongst Luftwaffe crews this aircraft became derisively known as the Luftwaffenfeuerzeug (Air Force lighter).
Other problems also became obvious in service. Some units noted that the wings became deformed after as few as 20 flights.
Later versions incorporated strengthened wings, but this further increased overall weight. Subsequent iterations of the He 177 introduced improvements such as a redesigned and more streamlined nose section and additional armament, but none addressed this type’s fundamental problems. During one of the last large-scale uses of the He 177, Operation Steinbock, a strategic bombing campaign against targets in southern England, 14 He 177 A-3s were used in a single mission.
One had to abort when one of its massive mainwheel tyres punctured during taxiing. Eight of those that did take off were forced to rapidly abandon their attacks and return to base due to engine fires or overheating. And these were all new, factory-fresh aircraft!
By the summer of 1944, the use of the He 177 was basically abandoned due to a combination of its continuing reliability issues and a general shortage of fuel.
The He 177 was proof that innovation is not always a desirable attribute in a combat aircraft. Almost every aspect of its design was compromised by a narrow focus on drag-reduction at the expense of simplicity and reliability and by changes forced by the ridiculous demand that it should become a dive-bomber.
When it worked, this bomber could be effective. It could carry over 12,000lbs of bombs and, in a shallow dive, it could maintain a speed of close to 400mph, too fast for interception by most Allied fighters. The problem was that it rarely worked.
The biggest surprise was that so many examples of what was obviously a seriously flawed design were produced. Almost 1,200 of all variants of the He 177 were produced between November 1942 and June 1944. Many later production examples were never used due to fuel shortages, and though precise figures are difficult to find, most sources suggest that far more of this type of aircraft were lost to engine and other failures than to enemy action.
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In response to engine fires, Heinkel began work on a new version, designated the He 177B, in 1943. This was to use the same basic airframe, but with lengthened wings incorporating four Daimler-Benz DB 603 engines in separate nacelles.
This might have addressed the He 177’s most notable problem, but this version never went beyond the creation of a handful of prototypes. The conclusion is clear: the He 177 was a bold and innovative design but a seriously flawed combat aircraft.
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- Crew: 6
- Length: 22.00 m (72 ft 2 in)
- Wingspan: 31.44 m (103 ft 2 in)
- Height: 6.67 m (21 ft 11 in)
- Empty weight: 16,800 kg (37,038 lb)
- Powerplant: 2 × Daimler-Benz DB 610 24-cylinder liquid-cooled piston engines, 2,218 kW (2,975 hp) each
- Maximum speed: 488 km/h (303 mph, 263 kn) at 6,000 m (19,685 ft) in level flight
- Range: 6,000 km (3,700 mi, 3,200 nmi)
- Service ceiling: 8,000 m (26,000 ft)
- Rate of climb: 3.167 m/s (623.4 ft/min)