Heinkel He 177

infobox Aircraft
name =He 177
type =Heavy bomber
manufacturer =Heinkel Flugzeugwerke

---

caption = He 177 A-02 production prototype
designer =
first flight =November 1939
introduced =1942
retired =1945
status =
primary user =Luftwaffe
more users =
produced =
number built =~1,184
unit cost =
developed from =
variants with their own articles =Heinkel He 274
Heinkel He 277

The Heinkel He 177 "Greif" (Griffin) was a long-range bomber of the Luftwaffe. The troubled aircraft was the only heavy bomber built in large numbers by Germany during World War II. Aircrews nicknamed it the "Luftwaffenfeuerzeug" (Luftwaffe's lighter) or the 'Flaming Coffin' due to the engines' tendency to catch fire on the early versions of the aircraft. Price 2004, p.162.]

Earlier versions had many problems; when the problems were solved the type was successful, but could not be deployed in quantity due to Germany's deteriorating situation in the war.

Design

The He 177 was conceived as a result of an "Reichsluftfahrtministerium" (RLM) requirement called the Bomber A specification which called for a bomber aircraft more advanced than the Dornier Do 19 or Junkers Ju 89 "Ural-Bomber" prototypes, capable of carrying a bombload of at least 1,000 kg (2,204 lb) over a range of 6,695 km (4,160 miles). The aircraft had to possess a maximum speed of about 540 km/h (335 mph) at altitude and it had to embody sufficient structural strength to enable it to undertake medium degree (later changed to 60 degree) diving attacks. In order to meet these specifications the He 177 embodied many advanced features including coupled engines with surface evaporation cooling and small remotely controlled defensive gun turrets.

Engines

An unusual feature of the aircraft was the use of twin engines in each nacelle driving a single propeller, as the components of a "power system". Siegfried Günther, chief designer of Heinkel, chose to use the Daimler-Benz DB 606, which consisted of two Daimler-Benz DB 601 engines coupled together to use a common propeller, in order to minimise drag. The two engines were coupled side by side in each nacelle and inclined inwards at the crankcases' upper surfaces, so that the inner cylinder banks were disposed almost vertically, a single gear casing connecting the two crankcases, and the two crankshaft pinions driving a single airscrew shaft gear. The insistence of this engine configuration stemmed directly from the RLM's determination that the He 177 should be capable of dive bombing. The use of only two propellers on a heavy bomber also offered a substantial reduction in drag and a marked improvement in maneuverability. Indeed, the initial prototypes and pre-production models of the bomber had an airspeed and maneuverability comparable to many heavy fighters of the time.

Both the DB 606 and 610 coupled "power systems" had A and B versions, signifying opposing rotation directions when in operation-the He 177 V1 through V3 prototypes all had the A-1 version, that rotated counterclockwise when seen from the front, used on both sides, while all later 177s, from the V4 prototype onwards through the entire production run, used one A- and one B-version of the engines, using one of the clockwise-rotation B-versions on the port-side wing.

The paired engines had first been introduced on the single-propeller equipped Heinkel He 119 prototype reconnaissance bomber aircraft to reduce drag where they worked well, but their extremely tight installation on the He 177 led to considerable problems, the most common being in flight engine fires and overheating. There were several reasons for the flammability of the DB 606 engine, one of which was the common exhaust manifold on the two inner cylinder blocks, which became excessively hot and caused 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 injection pump to deliver more fuel than was required by the engine, in addition to which the injection pump connections leaked. In order to restrict the aircraft's weight, no firewall had been provided, and the DB 606 was fitted so close to the mainspar that there was insufficient space for the fuel/oil pipelines and electrical leads. The engine was frequently saturated by fuel and oil from leaking connections. At altitude, the oil tended to foam partly as a result of the oil pump being overly effective, and in this condition it circulated in the engines, its lubricative qualities being severely reduced. The lack of adequate lubrication resulted in the disintegration of the connecting rod bearings which burst through the engine crankcase, puncturing the oil tanks which poured their contents on to the hot exhaust pipe collector. The tightly-packed nature of the engine installations also led to very poor access to the engines. As a result of these factors, as well as a lack of routine maintenance in the field, the DB 606 easily caught fire in flight. Thus the effort to create an adequate engine to power the He 177 (such as the Junkers Jumo 222 produced too late in the war), by mechanically coupling pairs of lower-power engines, while theoretically sound, proved to be difficult and time consuming to perfect, leading to engine complications especially on the initial production models.

Starting with later versions of the He 177A-3, a modified engine nacelle with a new engine, the Daimler-Benz DB 610, was used to attempt to eliminate tendency for the engines to catch fire. Several improvements concerning cooling issues for the engines by setting a power limitation resulted in greater reliability. This modification was successful as far as engine fires were concerned but there were other minor problems with the transfer gearbox between the two engines and their shared propeller and other difficulties involving the installation of flame damper tubes for night missions.

urface evaporation cooling

Originally, the He 177 design called for evaporative cooling in order to eliminate radiator weight and drag, but despite the immense amount of research undertaken by Heinkel into the problems of surface evaporation cooling, this feature was soon abandoned in 1939 in favor of annular radiators, one fitted directly behind each propeller, which resembled those fitted to the Junkers Jumo 211-powered versions of the Ju 88. The addition of large radiators added significantly to the aircraft's weight and drag.

Armament

Another design innovation featured by the He 177 as originally conceived was the use of three remotely controlled defensive gun turrets, which offered substantially less drag than manned turrets. Unfortunately, the perfection of these turrets was slow, and the He 177 had to be modified to accommodate larger manned positions, this requiring the fuselage to be strengthened in several locations, further increasing the aircraft's weight and drag. Most of the He 177As produced did have a single, twin MG 131 gun remote dorsal turret, located forward of the aft-located, manned dorsal turret, and sighted from a transparent dome just behind the forward cabin area.

Experimental weapon loads

In addition to carrying a variety of torpedoes, and guided missiles such as the Hs 293 anti-shipping missile, the 177 was tested with a number of unorthodox armaments. The first of these experimental weapon schemes known to have been attempted were the twelve examples of the He 177 A-1/U2 "Grosszerstörer" variant, which was armed with a pair of limited-traverse 30mm MK 101 autocannons in the extreme front of a dramatically enlarged under-nose "Bola" gondola, and intended, variously, for "train-busting" ground attacks and possibly long-range anti-ship raids. 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 177s, fitting a massive 50mm cannon to the planes' nose gondolas. This variant was unofficially dubbed the "Stalingradtyp". Although a small number of later A-3/R5 models were to be built from scratch, with an even larger "Bordkanone" BK 7.5, 75mm ventral cannon, structural stress problems caused by the gun's recoil meant that the "Stalingradtyp" did not see combat use outside of the original improvised handful. Three later-model 177s were experimentally equipped in June 1944 with batteries of obliquely-mounted rocket mortar tubes (thirty-three in all) to create the "Pulkzerstorer" (Formation Destroyer) flying battleship. (The term was also used for the "Werfer-Granate 21" rocket-firing Luftwaffe single engined fighters.) The mission of these specialised aircraft was to stalk and destroy Allied bomber formations. Bomb bays and auxiliary fuel tanks were deleted on these aircraft in order to house the spin-stabilized rockets and their firing mechanisms. The tubes could be fired individually, simultaneously, or in two salvoes of fifteen and eighteen. Tests with fixed balloon targets showed the potential of this system, and limited operational trials against US Eighth Air Force bomber streams were authorised. These trials yielded no results, however - each time an attack was attempted the" Pulkzerstorer" 177s were unable to close to firing range with their targets. It is also believed that a single heavily modified He 177 was prepared as a prototype for a projected nuclear bomber variant,the "Greif" being deemed the best compromise choice for the role until the arrival in operational service of more suitable carriers, such as the Junkers Ju 488 four engined derivative of the Ju 88, or the jet-powered Junkers Ju 287.

Wings and undercarriage

The insistence on the ability to dive-bomb also led to the need to strengthen the wing structure, leading to the classic "vicious circle" in military aviation design, starting with an increase in unloaded weight, producing the need to enlarge the undercarriage, in turn increasing further the weight and causing a decrease in speed, range and carrying capacity. The requirement to dive-bomb was never satisfactorily solved and the later versions of the aircraft were produced without dive brakes.

The He 177's main gear arrangement can best be described as complex. There were four main gear struts, each with one large wheel, with the inboard and outboard retracting sets almost "meeting" under the nacelle of each of the engines when fully extended. A more conventional single-leg twin wheel arrangement for each main gear was actually used on the sole example of the He 274, and a few developments that only existed as drawings actually had tricycle landing gear setups being fitted to the He 277.

Airworthiness and handling

British Royal Navy test pilot Eric Brown related in his book, "Wings of the Luftwaffe", about the amazingly "light" handling of the He 177 A-5 version, one of which he flew as a captured aircraft late in the war. His remarks also seemed to indicate that the He 177's elevator control forces, in particular, were all too "exceptionally" light for a plane, which was no more than two feet different in wingspan and fuselage length, and with a similar empty weight, than the American USAAF's famous B-17 heavy bomber, and that reports of He 177's breaking up in flight could have been partially due to such light elevator control forces fooling He 177 pilots into thinking that they could "horseplay" with the control yoke in the pitch axis, over-stressing the "Greif's" fuselage to the point of structural failure.

Operational history

Beset by many other technical difficulties in development and service, the plane had a troubled life. This was in part due to overly optimistic design requirements of long range, high speed, heavy bomb load, and dive bombing. Though Goering forbade Heinkel to develop a version with four separate nacelles, Heinkel nevertheless produced prototypes of the Heinkel He 177B (later renamed Heinkel He 277) which was produced in limited numbers.

Although the He 177 entered service in 1942 it was still far from operational. As an emergency measure it was used to supply the encircled 6th Armee at Stalingrad where it was determined that it could only carry about the same payload as the appreciably smaller Heinkel He 111, and was useless for the evacuation of wounded troops. As a result the He 177s reverted to bombing and flak-suppression missions in support of the Wehrmacht in the vicinity of Stalingrad. Only thirteen missions were flown and seven of the He 177's crashed in flames without any action attributable to the enemy.

Another example often cited is a night attack on England during Operation Steinbock (early 1944): 13 aircraft took off, 1 failed to take off due to a burst tire, 8 returned with burning or overheating engines, and of the few that got to their target two were destroyed by enemy night fighters. It is not always clarified that these aircraft were brand new, delivered about a week before and not even properly flown-in, as the air unit had moved to a new airfield the day before and lacked sufficient maintenance personnel and material.

During later operations like Operation Steinbock ("The Little Blitz" or "The Baby Blitz") with an average loss rate of 60% for each type used (Do 217, He 111, Ju 88, Ju 188), the He 177A-5s had a loss rate well below 10%, making them the best bomber used in this campaign. According to sources experienced crews were able to carry a 5,600 kg (12,345 lb) payload on these missions. Standard tactics for the He 177 was to climb to its service ceiling before crossing the French coast, then carry out the rest of the mission in a shallow full power dive, which allowed the aircraft to reach a speed of over 690 km/h (428 mph). The higher speed and constant change of altitude made the aircraft harder to intercept, increasing the survivability of the aircraft, but greatly decreased bombing accuracy and effectiveness.

From late 1944 high-grade fuel was not available in the quantity needed to operate a whole Geschwader of He177s and the Emergency Fighter Program. By this time the He 177 had become the most reliable, rugged and technically advanced bomber of the Luftwaffe. This was confirmed by postwar tests on the He 177A-5 and the single long-range He 177A-7, which the RAF found impressive. The He 177 can be compared with the Boeing B-29 bomber which also took about two years to have its problems ironed out, after which it became one of the most successful bombers of aviation history. Due to the war situation in Germany the He 177 was never able to prove itself and its designs.

Variants

;He 177 V1-V8:First prototype (V1), 8 prototypes built in total. V4 aircraft first to use opposite-rotation propellers with DB 606 A/B engines, as all later production series aircraft would. ;He 177 A-0:Pre-production series, 35 built.;He 177 A-1:First production series, 130 built.;;He 177 A-1/R1:First version to use the FDL B 131 remotely aimed/fired forward dorsal turret.;;He 177 A-1/U2:"Grosszerstörer" heavy fighter with twin MK 101 30mm autocannon in "chin" lower nose mount, twelve conversions.;He 177 A-2:Proposed four-man pressurized variant with reduced defensive armament (six MG 81 and single MG 131 guns);He 177 A-3:Second production series, 170 built. Sixteenth and subsequent aircraft powered by DB-610 engines.;;He 177 A-3/R1::Powered by two Daimler-Benz DB 606A/B piston engines.;;He 177 A-3/R2::Modified defensive armament - MG 151/20 installed in tail position.;;He 177 A-3/R3::Anti-shipping version capable of using Henschel Hs 293 glide bomb.;;He 177 A-3/R4::Fitted with FuG 203 "Kehl III" missile-control equipment. ;;He 177 A-3/R5::"Grosszerstörer" version armed with "Bordkanone" BK 7.5 75 mm gun (based on the PaK 40 cannon) in ventral gondola,, as also used on the Ju 88 P-1, project only.;;He 177 A-3/R7::Torpedo bomber version abandoned in favor of the He 177 A-5, three built.;He 177 A-4:Proposed high altitude version later developed into the Heinkel He 274.;He 177 A-5:Main production version with increased maximum external bombload, 826 built.;;He 177 A-5/R1:Version optimized for Hs 293 and Fritz X guided bombs, with "Kehl" control gear.;;He 177 A-5/R4:Simplified bomb rack installation, equipped with "Kehl" control gear for guided ordnance.;;He 177 A-5/R5:Twin MG 131 remotely aimed/fired guns in rear of gondola for rear ventral defense, project only.::A-5 "Pulkzerstörer" anti-bomber variant, armed with 33 spin-stabilised rockets obliquely mounted in fuselage, supplanting bomb bays and auxiliary fuel tanks. Three examples delivered in June 1944 for operational trials.::A-5 "Stalingradtyp" variant armed with "Bordkanone" BK 7.5 75 mm gun for flak suppression and ground attack missions;;He 177 A-5/R6:Reduced bomb bay capacity.;;He 177 A-5/R7::Pressurised cockpit study only, with A-2 version's reduced armament.;He 177 A-6:Long range, high altitude bomber with increased bombload and defensive armament. Six built as the He-177 A-6/R1. This version also had a tail turret and the capability to carry Henschel 293 missiles. ;He 177 A-7:Conversion of six He 177A-5 airframes which were intended to have a 36 m wing, and with DB 610 engines instead of the intended 3,600 hp DB 613 engines.

Production

Production of the He 177 till 30 November 1944:

Source: Bundesarchiv/Militärarchiv Freiburg

Operators

;flag|Germany|Nazi:
*Luftwaffe
**Fernkampfgeschwader 50
**Kampfgeschwader 1
**Kampfgeschwader 4
**Kampfgeschwader 10
**Kampfgeschwader 40
**Kampfgeschwader 100
**Kampfgeschwader 200
**Flugzeugführerschule (B) 15
**Flugzeugführerschule (B) 16
**Flugzeugführerschule (B) 31
** Wekusta/ObdL

;FRA:
*French Air Force operated at least two He 177A-3 abandoned by Germans and rebuilt by SNCASE at Blagnac.

;UK:
*Royal Air Force
**RAE (Farnborough) tested one He 177A-5. Aircraft (formerly F8+AP from 6./KG 40) was captured by French Resistance in September 1944 at Toulouse-Blagnac airfield. Transferred to the UK was repainted with British roundels and serialled TS439. [ [http://www.flightglobal.com/PDFArchive/View/1945/1945%20-%200902.html Flight International May 1945] ]

Possible survivors

During the period of the war when He 177s were based in the occupied Soviet Union, a small number of Griffins were known to have force landed on frozen lakes within that territory, which then could have sunk to those lakes' bottoms when spring thaws melted the lake ice. As no He 177s were to survive intact well past the end of the war (all known captured He 177 example aircraft, as well as the sole prototype He 274 in France, had been scrapped by the end of the 1950s) those possible sunken Griffins-many of which were based at forward Luftwaffe fields during the war, whose sites are now located mostly in the southern Ukraine, such as a major base that was located near Zaporozhia during the war-would be the only known surviving examples of the He 177, but none have yet been discovered as of 2008.

pecifications (He 177 A-5)

aircraft specification
plane or copter?=plane
jet or prop?=prop
crew=5
length main=22 m
length alt=72 ft 2 in
span main=31.44 m
span alt=103 ft 1 in
height main=6.7 m
height alt=21 ft
area main=101.5 m²
area alt=1,092 ft²
empty weight main=16,800 kg
empty weight alt=37,000 lb
loaded weight main=31,000 kg
loaded weight alt=68,340 lb
engine (prop)=Daimler-Benz DB 610 (twin DB 605)
type of prop=24-cylinder liquid-cooled inline engines
number of props=2
power main=2,950 hp
power alt=2,170 kW
max speed main=565 km/h at 6,100 m
max speed alt=350 mph at 21,000 ft
combat radius main=1.540 km
combat radius alt=960 mi
ferry range main=5,600 km
ferry range alt=3,200 mi
ceiling main=9,400 m
ceiling alt=30,800 ft
loading main=319.9 kg/m²
loading alt=65.6 lb/ft²
power/mass main=110 W/kg
power/mass alt=0.067 hp/lb
armament=
* 2 x 20 mm MG 151 cannon
* 3 x MG 131 machine gun
* 3 x MG 81 machine gun
* up to 7,200 kg (15,873 lb) of bombs or 3 guided missiles Henschel Hs 293 or Fritz XUsual configuration:
* 48 x 70 kg bombs (3,360 kg/7,405 lb total)
* 10 x 500 kg bombs (5,000 kg/11,020 lb total)
* 6 x 1000 kg bombs (6,000 kg/11,224 lb total)
* 2 x 2500 kg bombs (5,000 kg/ 11,020 lb total)or
* 2 Hs 293 + 1 Hs293 remotely controlled missiles under the fuselage
* 2 Hs 294 + 1 Hs 294 remotely controlled glide bombs under the fuselage
* 2 PC 1400 + 1 PC 1400 gliding bomb under the fuselage
* 2 torpedoes + 2 torpedoes under the fuselage

ee also

aircontent
related=
*He 274
*He 277

similar aircraft=
*Avro Manchester

lists=List of military aircraft of Germany

see also=

References

Notes

Bibliography

* Chant, Christopher. "Aircraft of World war II". Grange Books, 2000. ISBN 1-84013-336-8.
* Darling, Kev. "Heinkel He 177 (Warpaint Series No.33)". Milton Keynes, Buckinghamshire, UK: Hall Park Books Ltd., 2000.
* Griehl, Manfred and Dressel, Joachim. "Heinkel He 177-277-274", Airlife Publishing, Shrewsbury, England. ISBN 1-85310-364-0.
* Hirsch, R.S.; Feist, Uwe and Nowarra, Heinz J. "Heinkel 177 "Greif" (Aero Series 13)". Fallbrook, CA: Auro Publishers, Inc., 1967. ISBN 0-8168-0548-2.
* Mondey, David. "The Hamlyn Concise Guide to Axis Aircraft of World War II". London: Chancellor Press, 2004. ISBN 1-85152-966-7.
* Munson, Kenneth. "Bombers 1939-45". London: Bounty Books, 2004. ISBN 0-7537-0919-8.
* Price, Alfred. "Heinkel He 177 Greif (Griffon)". "Aircraft in Profile, Volume 11". Windsor, Berkshire, UK: Profile Publications Ltd., 1972, p. 265-288.
* Price, Alfred. "He 177 Greif: The Luftwaffe's Lighter". "International Air Power Review". Volume 11, Winter 2003/2004. Norwalk, Connecticut, USA: AirTime Publishing, 2004. ISBN 1-880588-60-9.
* Smith, J.R. and Kay, E.L. "German Aircraft of the Second World War".London: Putnam, 1972. ISBN 85177 836 4.

External links